It would appear as though this has been a bad month for Microsoft. We started the month with the IIS FTP DoS and now, less than 24 hours before Patch Tuesday officially kicks off, we have a SMB BSD (reportedly affecting Vista, Windows 7 and possibly 2008). I have confirmed that it works against Windows Vista. The report, along with source code, was released on the vulnerability discoverer's blog

Microsoft's !exploitable Crash Analyzer reports the following:

1: kd> !exploitable
Warning: Unable to read from the TEB in the current thread.
Warning: Unable to read from the TEB in the current thread.
Exploitability Classification: UNKNOWN
Recommended Bug Title: Data from Faulting Address controls Branch Selection starting at srv2!Smb2ValidateProviderCallback+0x00000000000004ec (Hash=0x4f46440f.0x7c4b5e55)

The data from the faulting address is later used to determine whether or not a branch is taken.

The standard advice of blocking ports 139 and 445 is pretty solid here, and another option for people (a standard step I take before attending any conferences) is to disable the server service.

nCircle customers can use the following Focus query to find vulnerable systems:
(os:"Windows Vista" or os:"Windows Server 2008" or os:"Windows 7") AND app:"Direct SMB"