Thanks to the work of Matthew Mastracci, this amazing news is all over the net, but I want to mention it here.
My Treo 650 (from Sprint) has been working fine for me. The only real issue I have is the Sprint Service in West Philadelphia. I want to use it as my primary phone (and do, and just put up with the missed calls), but there are still issues of service coverage while inside my house. These super thick brick walls are just not nice to the Sprint signals. Other than that ChatterEmail has been superb, and I use it most of the day to keep me on top of my email, when I’m not in front of a computer. In that respect the Treo has been near flawless. I have no plans to flash Linux onto it, but I can see how it could become very interesting on the 650: with the keyboard, built in connectivity and a decently rezed screen.