T-Mobile Will Begin Selling 3G Next Year

No, they are not done. They said they have been working on upgrading the equipment to be ready for the rollout of NYC areas by next year. They said that 50% of their NYC network was finished. Just cause they didn't have the spectrum doesn't mean that they couldn't go ahead and build out the equipment to have it up and set. The faster they roll, the faster they can turn on the switch for 3G service. Thats the reason why they were so agressive in the auction, cause they know where they are putting up equipment and are going to offer service in non-current service areas like the Carolinas and other locations.

only network engineers know
keep in mind, T-Mobile keeps building up nodes, and probably some newly built nodes have inactive 3G equipment builtin, just wait for license and setup
if so, the deployment will be way faster, faster than everybody expected