AMD released their highly anticipated Bulldozer CPUs last week (our review). The reception was not very warm, and a common thought was that Bulldozer didn't perform as well as expected. Especially in single-threaded tests, Intel was still miles ahead, and even in multithreaded tests AMD wasn't a clear winner.

The initial CPUs use B2 stepping, but an AMD BIOS and kernel document already shows reference to unreleased B3 stepping. A stepping update should bring improvements (usually minor) to performance and power consumption, as well as possible bug fixes. Stepping updates are a normal way to provide small upgrades in between bigger ones, such as die shrinks and microarchitecture changes. While B3 stepping may help Bulldozer a little bit, it's very unlikely that a stepping update would provide huge benefits and thus make Bulldozer significantly better than Intel's equivalent CPUs - so waiting for this update is not exactly a good idea.

No timeframe for the update is known but if the past has any meaning, it won't be anytime soon. For example C3 stepping came about 9 months after the original release of Phenom II X4 with C2 stepping. 

Source: AMD (page 27)