I recommend the Powershot S1 IS as well. I used it for 2 weeks on vacation and have been unsatisfied with my regular camera (powerhsot A75) ever since. Here's why I like it so much:
10x optical zoom (gets you damn close to whatever you wanna shoot)
Fast Lens (f3.1 at full telephoto)
Image Stabalization (helps a lot in getting those low-light shots that need just a little bit slower of a shutter speed)
EXCELLENT Video Mode (640x480 at 30 FPS, with image stabilization and zoom both functional in video mode)
Great burst mode shooting (with a fast enough memory card, there's no way to fill up the cameras buffer)
Flip Out LCD (lets you get a wider variety of angles (i.e. shooting above the heads in a crowd, ect))
Ultra Fast/Quiet Zoom Motor (gets to 10x optical zoom in 1 second, without the grinding you'll hear in other digicams)
Optional Remote Control
Uses Compact Flash (cheapest type of memory)
Compact compared to other cameras in its class - the only other comparable one, in my opinion, is the FZ10, and it way bulkier.
I'd try one out and see what you think.
~Cris