Hah! Good call, Author.
I can probably be categorized as semi-pro, since I do shots of the machines my business builds. And I just got a 550d to supplement my Nikon D80... Actually, I got it to do HD video; it wasn't any more expensive than a normal camcorder that can do 1080, and is vastly more flexible.
The video is quite good, though I was forced to shoot fairly high ISO; I haven't had much time to evaluate its photo ability yet. Compared to the D80, though, it shoots MUCH faster, the AF is a ton faster and more reliable, and it focuses much more closely - maybe 15cm as opposed to 50cm for the Nikon's kit lens. High ISO performance seems a lot better at first blush, and it seems to do a better job of handling exposure in full auto mode as well - the D80 will reliably blow out fluffy summer clouds in a landscape shot, and the Canon seems to handle that well.
But... it's tiny, the lens is tiny, and the ergonomics are truly awful. The conniptions required to change settings, and the truly bizarre UI quirks (three buttons are required to delete an image, as opposed to one double-press on the D80) are kind of crippling for serious use. It's a shame that a camera with such potential is such a pain in the ass to use.