Part of that is the 'megapixel' factor (beyond technology improvements). I think the Rebel DSLR is a 6Mpixel. Where the Rebel will have an advantage is in low light. It will do better in focusing speed, flash depth(how far it can throw the flash) and have less noise in the images. The SD950IS will have noise start to creep in after ISO 100. The Rebel should be able to run up to ISO 400 without problems. For pictures in bright daylight, the SD950IS should do a lot better.
Actually, it's 8mp. Though if I waited the XTi is 10.1mp. And the latest addition the XSi will be 12.1mp. Doh, if I only waited.
