Yup, rc5 now has a windows 32-bit stream beta client. I've got it running on a HD 4650. It crunches out a work unit in 24 secs. While not one of the ball of fire stream cards, it is still a respectable output. Installation was simple and everything worked the first try for me.
So if ya have an ATI Stream card just sitting around, give it a shot and help the team out a bit.