Funny you should post this because I was pondering the exact same thing today. I was referring to it as 'throttling the bubble'. It seems likely to be having an effect. That is, if Mtgox suddenly was magically able to complete all the verifications in their backlog TODAY, presumably all those people would immediately try to buy bitcoins, which would REALLY cause the price to skyrocket.
I mean, assuming those people weren't waiting for verification to sell a bunch of bitcoin so they could cash out a bunch of fiat...
Theres no need to wait for verification to sell - you could deposit $1m in bitcoins and sell them all unverified right now, but you'd have to verify to get the fiat out. Shouldn't stop those who think the price is about to dip from selling now...