All those new ASIC miners coming online? The difficulty jump over the last month is intense: http://bitcoindifficulty.com edit: This is a pretty good quick wrap up of what I think is going on here: http://chralash.wordpress.com/2013/09/17/the-new-pseudo-bubb...
Quibbling about the current valuation misses the point. The secure transfer mechanism is the real value, and is not getting shoved back in the bag. Bet long on BTC and I doubt very highly you'll regret it, even if you get in at 200US and lose over the next few months.