I couldn't help but notice that of the top users on all the sites, the majority are from outside North America:
Server Fault: 60% of the 10k users (SF only has 10 10k users)
Super User: 60% of the 10k users (SU only has 10 10k users)
Stack Overflow: 40% of the top 10 users (to keep the field even)
(users with no location specified were counted, but to err on the side of caution, were counted as North America).
Is this because people in NA are working harder, and thus have less time to spend answering questions? Or is it because the other timezones are so far off the NA timezone that we're not competing with so many other people answering?
Either way, I think the message is clear: If you want to rep-whore, do it outside of the NA business hours!