A few sources close to AMD have confirmed that the Shanghai server part will be the first 45nm to launch. Deneb, a 45nm quad-core for desktop market will follow.
This was the same scenario like last year, where Barcelona was launched more than a month before AMD has introduced Agena, its desktop core.
The server market, as well as the Desktop market, needs some faster players and Shanghai makes an opportunity for a quick return as a stronger player. Shanghai at the same time has a nasty task of competing with Intel's Nehalem server part that looks to be stronger than ever.
Intel also has a 12-core CPU codename Dunnington that will certainly get a lot of attention. Shanghai will have smaller die and it should do fine against 45nm Harpertown CPUs.