Bubble? Bitcoins are trading at the same price they were 2 weeks ago (at least it was last night, as I type this the price is already back up to $20...). I think this should be considered normal market volatility more than anything like a bubble burst.
I almost feel like "bubble" is now just a buzzword that was mentioned on the forums a few times and now all these people that know nothing about markets are repeating it ad nauseum.