AMD representatives already announced in mid January that Barcelona processors with B3 core stepping should start sampling this quarter. According to CNET.com referring to recent AMD officials" statements, the company started sampling Barcelona processors based on B3 core stepping to its server partners last week.
Server Barcelona processors with new K10 micro-architecture didn"t really get widely spread yet because of the notorious "TLB bug" that resulted in stability loss in case all four processor cores were loaded heavily. This problem occurred mostly in the server segment that is why server solutions manufacturers looked forward to new B3 core stepping that was free from this unpleasant bug.