Moreover, it was only a couple of days ago that you could fund your bitcoinica account with BTC (as opposed to money).  Until then it was too much work for me to do that, even though I too was beating the bear drum.

The other problem with shorting: the money making premise is based on the fact that something is overvalued.  When there's no rational tie between pricing and value what's to keep it from becoming vastly more overvalued before it crashes?  5:1 leverage is very much a double edged sword.  You could get a margin call and lose a fortune while still being right.  

Add to that unlimited downside with limited upside and it takes iron discipline to trade short.  A short position is not something you can leave open while not looking.