Every time I go on facebook now I see ads asking if I want to advertise even tho I am already running ads.
Also I read that their advertiser base had increased by 3 times in the last 6 months (sorry cant remember where I read that.. techcruch maybe). More advertisers = more competition and higher CPC
ok more competition, but not quadrupled bids in 2 days... from 0.29 - 0.45 to 2.54 - 3.33, no way it can be only competition