This is a quick message for anyone who wants to know what happens.
Our server's caching system screwed up and stopped to update the prices. The API prices and the chart are completely fine. Only website displayed prices are stuck. Mt. Gox's price was about 2.6 while Bitcoinica's remains at over 2.9.
We thought about reversing the trades since there were some people shorting at the high prices and hoping to buy back at the lower prices, as our system continued to shoot orders to Mt. Gox at 2.9, which can't be executed at all. (If not wrong you can see an ask wall there. I will cancel the orders soon.)
However, We would like to take this as a lesson and we won't reverse the trades in this incident. But do expect a large spread due to a sudden growth of pending orders.
Now many traders are starting to buy back and our net position will recover soon.
For the previous weeks, I have been working on the next release of Bitcoinica, which will be much more robust than the current release. I have no plans about the release date but I make sure everything's right by then. This is also why there weren't any new features came up on Bitcoinica recently except for bug fixes.
Once again, we apologize for the problem and enjoy your trading at Bitcoinica!