One way you can hedge against bitcoins is by making a bet on betsofbitco.in. I could, for example, register a bet that bitcoin will have a value of under $10 USD by the end of May 2013.

However, you are limited by your ability to find a counterparty. Of course, willingness to find a counterparty is a limit in most forms of short or put. Judging by some of the current odds on other bets, finding counterparties to small bets of large swings downward might not be that hard. That particular forum seems to think that bitcoin will go up. Of course getting paid in bitcoin for your bet that bitcoin will drop might be a problem...