I have a Canon SD850IS (SD850 for short). It has some things I don't like about it but I wanted the 140mm (4x from normal angle) zoom and ultra compact-ness which only it (and one other whose name I forgot) has. I would recommend it if you want that extra zoom. The 3x zoom from normal angle (36mm focal length) is almost ubiquitous. I know some of you are hard pressed to stand back far enough to get everyone (or everything you want) in the picture. Canon also makes a super compact camera with a wider angle lens (28mm in 35mm film camera equivalent). This model, the SD800, also has the usual 3x (105mm) from normal angle zoom (3.8x from the wideest angle).
What I did not like was a little blurring at the picture corners, and a quite feeble flash. Unfortunately these issues are the rule, not the exception, among point and shoots of all brands. Therefore you will need to read on-line and magazine reviews, or get word from friends, to find out the cameras that don't have these issues.
Because of lens limitations, IMHO more than 6 megapixels for a point and shoot is overkill unless you expect to do a lot of cropping, and enlarging of what is left. As well as print the entire picture as-is also, which is why you framed the picture that way when taking it.
Had I not needed the 140mm zoom I would have chosen a different camera from the SD850 although probably another Canon model.
(edited) Canon's naming is quite confusing with different names for the same camera as sold in different countries. The Ixus 850 is the wider angle SD800 mentioned above. The SD850 is also known as Ixus 950. There is an SD950 that is something yet different.
All point-and-shoots need a tripod or firm surface for good night shots.
Digital camera hints:
http://members.aol.com/ajaynejr/digicam.htm