Sorry, here in bitcoin land we don't short anymore. We tried it, but it just fucked everything up. Your only option is long.
Such a blatantly misleading claim can't stand uncorrected.
Fact is, we had some more viable short selling facilities. But there was no outright obvious effect on the rates. Some were able to detect some local effects, which could be quoted to support both the "pro" and the "contra" viewpoint.
And while we're about to correct FUD, it is also not true that e.g. a platform like Bitconica is outright financial hazard and must collapse necessarily. From a financial viewpoint, that platform was constructed in a sane manner and did work indeed -- mind me, without forcing the platform to bet against its customers.
What indeed
fucked everything up was the lazy attitude towards IT security and coding standards. Plus an overall unprofessional attitude towards any business best practices, like e.g. how to communicate with ones customers.
As others already pointed out, currently
http://ICBIT.se is the only simple and easy to use solution allowing to take a short position without the need to actually sell your assets. Don't expect too much, the market is still rather illiquid. But personally it served me well to hedge my BTC positions partially, especially at times as right now, where corrections are imminent.
PS: I know I know, proudhon always writes with a grain of irony, but the OP asked a plain and straight question and deserves a plain ans straight answer
