Just out of curiousity, does the Pentax IS system do tripod detection? Does it have a panning mode? Can it auto-detect the direction of panning motion?
Now Mark, honestly. You know the answers to these questions already, don't you? Of course you do.
Actually, I didn't know the answers. I suspected, but the answer wasn't in the review I checked.
I don't think that the in-body IS needs some of those as the correction is done at the actual sensor, not a couple inches away. The K10D system does do rotation as well as X and Y damping, which should theoretically help with panning, etc. Somehow, I don't really buy that these things, especially the direction of panning, will have any kind of noticeable impact on the effectiveness of the system. These are pretty slight tweaks.
I think you are mistaken. Canon IS systems (and I assume everyone elses) should be turned off when you intend to shoot while moving the camera (either panning shots or high speed shots while moving) because they cannot distinguish between intentional motion and unintentional motion. They'll attempt to correct the intetional motion and your picture will be worse rather than better.
With the Canon Panning mode, the camera knows to watch for motion in either the vertical or horizontal axis. When it detects that, it shuts the IS down. In fact, if it detects too much motion along both axis, it shuts off IS entirely. Contrary to some Canon user's beliefs, it does not correct for motion while panning diagonally.
For panning shots, it's not what I'd call a "slight tweak." It's the difference between having IS (along one axis) and not having IS at all. Given that panning shots are inherently long exposures, having some IS in those situations if very useful. As to its importance, that depends on how often you take panning shots. For me, that's not very often at all.
Mark, I don't mean this is a negative way, but obviously money is not as much of a concern for you (this can also apply in the HD camcorder thread). If money is no object (or at least, not much of an object), then naturally we'd all be using top-spec hardware. However, let's remember than the 1D is 4x more expensive than a K10D. I would hope that you get something for that money! The problem is that you get into severely diminishing returns. You certainly won't be taking 4x better photos than any $1k mid-tier DSLR.
Money is very much a concern for me. It's a question of priorities as much as it is an absolute budget. As I have said before, I'm not rich, I just have different priorities. Our family drives cheap cars for at least 10 year (I've never had a car with power windows); we camp during most of our travels; we own < $200 in jewelry, and we rarely eat out (and then usually at places with play areas
). It's all a question of priorities.
As for the 4x better photo argument, you don't seem to understand how to properly evaluate your purchase options. When comparing a $1K camera to a $4K camera, you don't check to see if the latter will produce 4x better photos. Instead, you look at the improvement in photo quality and number of "keeper" photos you get with the $4K camera and determine whether those improvments are worth the extra $3K. It's the marginal improvements compared to the marginal price increase that matter, not a comparison between the total numbers.
Let's uses lenses as an example. Canon makes two lines of high quality 70-200 lenses - one with an f/4 maximum aperture and one with an f/2.8 maximum aperture. The picture quality and just about any aperture other than f/4 and below is almost identical between the two. The f/2.8 costs twice as much. I bought the f/2.8 despite the fact that I expected to shoot only 20% of my shots at f/4 or below. My logic was that over the life of the lens, I would probably get an several hundred extra shots that I liked better with the f/2.8 lens compared to what I could get with the f/4.0 lens. Those several hundred shots were worth the additional $500 for the lens to me. That might be several hundred out of several thousands (and certainly not twice as many), but the marginal increase in desirable shots was worth the marginal increase in the cost of the lens.
The same logic applied when I purchased a 1Dm2 ($3,500) instead of a 20D ($1,300). I expected that I would increase me yield of "keeper" shots from about 2,000/year to 2,5000/year. In addition, about 20% of the other shots would be better shots with the better equipment. Not three times as good, but better nonetheless. I decided that the extra 500 shots per year plus the improvements to the other shots were worth the extra $2,200. There were, of course, other considerations (avoiding the frustration of knowing that I missed a shot because I bought the cheaper camera, getting more enjoyment from working with a better tool, increased exercise from toting heavier gear, etc.).
My main point is that the difference between spending X or 4X for gear doesn't result in 4 times more or better pictures. It should, if the purchase is made rationally, result in an increase in the quantity and quality of pictures that is worth the 3X price differential. For pros, the decisions are easier because they can more easily quantify their income difference attributable to different gear. For us amateurs, we just have to decide what the extra photos are worth to us. Deciding on the higher gear doesn't necessarily mean that we're cost insensitive, it just means that we put a higher value on photos compared with other spending (or saving) choices.
When Minolta introduced the first successful AF system, the other three major players had AF systems out within a couple of years.
Actually, I was just reading the other day, the Time-Life "Year in Photography" book from the early 1970s where they describe the first AF system.
I was careful to use the modifier "successful". Pentax and then Canon both came out with autofocus systems before Minolta, but they were market disasters. When Minolta came out with their system (and Nikon quickly followed), Pentax and Canon went back to the drawing board and came out with the systems that they essentially still use today.
When Canon introduced the first IS system, Nikon was able to offer a version only 5 years later (with Minolta and Pentax following 5 years after that). I wonder how long it will take for Nikon, Pentax, Sony, or Olympus to finally introduce a full frame sensor. Hopefully not too long; after all, they were only about five years behind on moving to the DSLR world.
Oh man, and some people claim that I beat the company drum too hard. You'd think that Canon was the only company to ever come up with anything new...
No, no no...you missed the proper flow of the religious debate. I sited Minolta's introduction of AF in the paragraph before for the very reason that it would show me giving credit to someone other than Canon for inventing something useful (it does happen on some rare occassions
) I was expecting you to counter with some of Pentax's many inventions, like TTL metering. Of course, Pentax's notable inventions were back in the 50's and 60's, so I would then dismiss them as ancient history.
I know that you keep flogging Pentax in a desperate bid to get their market share to sustainable levels. I, on the other hand, have real skin in the game. I'm looking out for my investment in Canon stock and it's down on the year. Incidentally, this discussion is best read after printing it on a Canon printer (using Canon inks), copying it on a Canon copier, and faxing over a Canon fax machine. Oh, and view it using Canon's image stabilized binoculars. Try stabilizing the sensor in that market, buddy.
I'm very happy with my choice.
I even had them print a big poster of my wife and son on Main St USA on one of their $100k printers...
The whole diamond thing is a total racket anyway, but most of us know that... the scumbag who came up with "two months salary" ought to be taken out and shot. Die, DeBeers, die!!! But that's a whole different conversation. 
