GT200 is 65nm.
This is a fact, wanna doubt it ? Do. But don't expect it to turn out being 65nm.
At least not in launch time ( a 55nm refresh in the near future is possible, and kinda expected ).

GT200 will be used at least for the flagship ( top end ) product and a high end product ( like G80 in the past with the GTX & the GTS ).

As for the naming scheme... Nobody knows for sure.
Could be a nVIDIA mix bag again.
Just like they renamed some G92 parts to GeForce 9.... they could be using GF9 for both G92b ( 55nm G92 ) and the GT200.
Nobody knows...