aristotle - 9:16 pm on Sep 23, 2010 (gmt 0)

That is one possibility - it seems outrageous, but so does this whole throttling idea in the first place, doesn't it.

Maybe Google has set a traffic limit for every domain as a failsafe mechanism to guard against the possibility that some outside agency might penetrate the ranking process, or find a way to manipulate it, so as to produce a huge flood of traffic to one site. The limits could be set high enough that normal traffic to most sites wouldn't be affected.