tedster - 9:21 pm on Jun 9, 2010 (gmt 0)

No doubt - I've definitely seen that kind of short term ranking boost.

I also think that QDF may be assigned to a query term based on an assortment of social buzz metrics - it's not a "set it and forget it" kind of thing for Google. I'd also imagine that a sudden spike in the number of people searching on a term could earn it a QDF tag for a while.