You really can't go wrong with a Canon or Nikon.
I would hold off on the 50D, as the 60D may be coming out soon.
Nope, no in-body image stabilization for the Canon line, though there has been clamoring for it. It's just in the lenses.
I own a Canon Digital Rebel XT, and more recently, a Canon 7D. On the Canon side of things, you can go to the Canon Digital Photography Forums (
http://photography-on-the.net/forum/index.php), see example shots from various cameras and lenses, hear what people think about the equipment, rumors, etc.