Hi,
I'm new to bitcoin but have done a lot of reading in this forum and on other sites. I have to say that I totally agree with the ones that complain about the lack of shorting. One of the main points why there are bubbles on this world are the short-sale constraints that obviously exist. And although politicians sometimes like to make us think that all the short-sellers are bad and should be forbidden, the opposite is the case. If the price of bitcoin
would be overvalued, there is no
good way of driving the value back to its fundamental value without the option to short. Just think of the American housing bubble: prices kept rising and rising. Although some people felt something is wrong, they couldn't do much because there was (almost) no way to short mortgages/MBS/ABS!

Let's see what the future brings and whether any exchange will offer a shorting option.