The S3IS is a very nice camera, and one I have been looking at too. It is a bit more expensive though than other superzooms because it takes video better than the rest. Infact, its excellent. Image quality from what I have seen is great, although with higher ISO's(+200) the noise starts to degrade the photos. I believe this camera also has a supermacro mode too, which allows extreme close-ups(if there is enough light).
Other choices in this area include the Panasonic FZ7, Kodak P712, Sony H2 and H5 and the Fuji S5600. The Sony's have a lot of purple fringing though, and the Kodak doesn't use regular AUTOart's like the Canon which might be an issue for you.