The day I bought the phone, the T-Mo store said they didn't have any cases/protectors (This was literally within a week of release), so I was going to get a generic one.
On my way out, though, I saw the clear "clamshell" case from T-Mo.
Works great *EXCEPT* sometimes getting keys right on the edge of the touchscreen to register can be a pain (Thank God for Swype).
In fact, I've gotten SO used to the case that when I take it off, it feels uncomfortable (and I even have trouble finding the side-buttons

)