Well camera phones are still a long way from rivaling digital cameras, and I dunno if they ever will, but right now there are phone cameras that are better than 3 or 4 year old digital cameras, so who knows.
Anyway, I know about these things cuz I've been developing vodafone live service for mobiles for 2 years now, it's my job you see. so i've seen lots of camera phones.
Generally speaking Nokia provides the best picture quality, and often the highest resolution too.
The Nokia 6600 has one of the best cameras as someone pointed out, better yet the first of the 1 Mega Pixel generation is already out by now, it's the Nokia 7610 and I've used it myself and it's very very good.
This is a sample picture taken by it, you judge for yourself:
http://img40.exs.cx/img40/2002/Image019.jpg
What do you think ?