just catching up on the TOCTOU chat - you guys have really covered all the bases. Think it is worth storing your chat as a wiki entry on the ramifications of delay in token refresh in Windows ACL's :-)
@AviD - under most Unixes, you can change the privileges of a process after you have initiated it, but if your privileges are revoked, the process won't be likely to know about it until next time you try to run it, or if it is told to check. Normally in the circumstances you are talking about, you would revoke privs then kill the process as a matter of course.
Although in saying that, the threat model is not usually that worried in the case of leavers and movers. In the case of dismissal where there is a perceived risk, you would kill the process and have them escorted from the building:-)
Lots of securing supply chains and the cloud, heavy focus on APT, and some excellent stuff from Cisco on IPv6. Interestingly Aaron Barr didn't do his talk, and the HBGary booth was empty...