OK, I am one in 2.2 turbosim with the old baseband.

I did help one of my friend to downgrade from 2.2 to 2.1 but the baseband remained at 02.28.00 so no luck even downgrade back to 2.1.

My source told me 2.2 support new turbosim out. But not stable at the moment.
My advise to those using turbosim on their lock phones-
Use pwnage tool if you want to upgrade to 2.2. It will remain the old 2.1 baseband.
For those upgrade the baseband, on to 2.2 on your locked phones you are virtually out of the possibility of software unlock if available in a near future.
Looks like the software unlock will be based on the old baseband 2.1 and not 2.2.