Got the 590IS a couple of weeks ago. It's a nice little camera, not shirt pocket sized but it'll fit into a safari jacket pocket. I like that it has a handgrip, unlike the SD shirtpocket cameras which are so flat. Also the SD cameras, as someone else mentions is too automatic. I also like a optical viewfinder, small though it is, to supplement the LCD. you can also save on battery life by not using the LCD, although I must admit that it's nice to look at all the feedback settings on the 2.5" LCD screen.
But the main reason I bought this camera is for digiscoping use. For regular work, I rely on my 20D DSLR. I paid $154 for the camera from B&H. No tax for California residents, and the shipping cost was included with the shipment of my spotting scope and other accessories.