I just upgraded to a Phenom II 975 BE with stock cooler and no OC and it's idling around 42c. 48-50c while running a game (tried Skyrim and Minecraft for only a few minutes).
I also ran prime for a very brief period (maybe 3 or 4 minutes)but when it hit 58c rather quickly and seemed like it intended to steadily climb I closed it.
AMDs product page states the max temp at 62c, which made me feel a bit more worried.
I already ordered a aftermarket cooler and some new thermal paste, I figured even if it isn't too hot it never hurts to be a bit cooler. I'm only asking because it won't be here till mid next week and I'm a paranoid worry-wort.