This [Sunday] morning Stephen Fewer released his long-awaited SMB2 code execution module for the Metasploit Framework. He plans to publish a whitepaper in the near future that discusses the exploit technique and the newly written Vista/2008 ring0 to ring3 stager code. This module is available in the 3.3-dev tree and supports Vista SP1/SP2 and 2008 SP1/SP2 (but not R2) with the same offsets and addresses. Keep in mind that the best workaround for this still-unpatched flaw is to disable the SMB2 protocol.
According to the exploit module...
This module exploits an out of bounds function table dereference in the SMB request validation code of the SRV2.SYS driver included with Windows Vista, Windows 7 release candidates (not RTM), and Windows 2008 Server prior to R2. Windows Vista without SP1 does not seem affected by this flaw.