Lynn Pettis (7/12/2012)
Although I got it correct, I think the true correct answer should have been Operating System Maximium. This would have taken the version of the OS out of the question.
In fact it could even be argued that the next big server OS may support 64 slots with a 12 core processor in each, giving 768 cores, and SQL Server 2008 R2 will then, without having changed in any manner at all, support 768 cores, so that the given answer 256 is definitely wrong.
256 cores is a reminder of the past for me - 256 processors is where we (ICL's 5G Systems Group) were going in the mid-80s.