There were apparently some rumors floating around at CES to the contrary. Everyone can keep their cool, it seems, as the guys at the Inq actually called up AMD & got the straight poop. Also insteresting is this tidbit:

"Basically there is no B4, there won't be a B4, and the next stepping is Cx. The Cx parts are the 45nm Shanghai cores, so the B3 will be the end of the line for 65nm."