Phandroid is claiming the Android Marketplace may be live with paid apps right now. However, they haven't been able to see any paid apps. Nor have I.
An app in their picture called "Aviator Watch" costs $1. I did a search of "Aviator Watch" and just "Aviator" but neither searches turned up anything.
I'm guess it's one of those "rolling roll outs" that's occurring with T-Mobile as they do with updates. Perhaps, it'll come our way in the morning.