Yes! Chris Witrak and Josh Wolonick write:

Some traders think the run-up in Bitcoin's value is irrational; for them, certain exchanges have made it possible to short the bitcoin.Simone Foxman reported earlier this week on two such exchanges: Bitifnex, a Hong Kong-based exchange that allows traders to open long and short positions in the bitcoin, and iCBIT, based in Stockholm, which allows traders to buy and sell futures contracts denominated in bitcoins.Another US-based exchange, Camp BX, allows margin trading, short selling, and flexible order-fullfilment options.