Like Frances, I'm a Canon fan. If you're looking for a good zoom and good all-round specs and generally high user satisfaction at a reasonable cost, take a look at the Canon A710is. 6X zoom, and has manual controls that the Olympus doesn't have - as well as an optical viewfinder that is lacking in the Olympus. Slightly larger, but still pretty small. Also has image stabilization like the Olympus. Very similar pricing, though far more happy users weighing in at dpreview. It's both a capable point-and-shoot for snapshots, and a camera that allows you to experiment a bit more. The Olympus is geared more to straight snapshots. The 800SD is also geared more to snapshots, in that there is not much in the way of manual controls.
I debated long and hard over the 710is vs. the Canon A640, as I wanted a capable point-and-shoot as a backup to my Canon Digital Rebel when we go to Europe later this year. Using a DSLR most of the time means I'm not happy without manual controls for at least some if not the majority of the time. The A640 is 10 megapixels, 4X optical zoom, has a rotating LCD (very handy for some shots!) all the manual controls, the option of adding 2X extenders and filters (already got the filters, since I could get some that worked with some of my Canon SLR lenses too!). It also takes standard NiMH AA batteries, which for me is a big plus, since if your batteries die, chances are you can replace them with alkalines pretty easily, unless you're far from civilization! Also uses SD memory cards, which are a somewhat more common format than the xD cards the Olympus uses. More common=cheaper and more choice.
http://www.dcresource.com/reviews/olympus/...iew/index.shtmlhttp://www.dcresource.com/reviews/canon/po...iew/index.shtmlhttp://www.dcresource.com/reviews/canon/po...ot_a710-review/Much depends on what you want to do with the camera. But I'd carefully consider the user reviews, the editorial reviews putting the cameras through their paces, and finally, going to your nearest dealer and seeing what you like when faced with the real McCoy.
And if you should decide to stray into DSLR territory, you might be interested in the new $599 Nikon D40.
http://www.dcresource.com/reviews/nikon/d40-review/