Flush-mount albums are hard bound books, covered in leather or some other sort of select material. Most have a choice between thicker pages (like a children's board book) or, one of the companies I use, has thiner style pages, but still ridged. The photos are actually hand-mounted to the pages and run flush to the edge of the page.
They really are beautiful... here are some pictures of one of my samples (the quality of the shots isn't so hot, but I was just taking some snapshots to show some other photographers the product when I got it in house). Everything is custom designed in-house by us. You can definitely see the difference between something like this and a shutterfly book.
This is the cover - it's actually a photo printed on a metal cover and then bound with leather.
They lay-flat and have no gutter so that pano prints are straight across.
The binding is all hand done and impeccable.
Here is an example of an album with the thicker pages - it's just aesthetics and what you like better.
It's still a lay-flat album (the spin isn't completely broken in on this particular sample), but this particular album has a 1/4 inch gutter split between the pages.
So yeah... when someone is talking wedding albums, there are sooooooooo many choices. These are two of the best companies out there (the company that makes the yellow album was just voted by the Professional Photographers of America as the best album presentation). And they definitely aren't cheap... but as I said before, total masterpieces when you are finished.
When the original poster made mention of looking at companies that only deal with pro-photographers, this is the type of album I thought they were looking for because, yeah, these companies only sell to established businesses and not direct-to-consumer.