According to http://www.techreport.com/discussions.x/13721 and somewhat confirmed by AMD:
B3 stepping isn't supposed to be available in quantity until the end of Q1.
An industry source at a tier-two reseller told The Tech Report that the TLB erratum has led to a "stop ship" order on all Barcelona Opterons. When asked for comment, spokesman Phil Hughes said AMD is shipping Barcelona Opterons now, but only for "specific customer deals."
B3 stepping isn't supposed to be available in quantity until the end of Q1.