I don't get it. Not so long ago Bitcoinica lost 40k BTC due to Linode hack, and they could afford to fully reimburse the amount and continue normal site operations. Now they've lost "only" less than half of it, and they're closing down? What did change in the meantime?
My guess is that before the FIRST loss hey had a bunch of BTC due to the quite high fees they charge. After the loss they were probably doing fractional reserve and rebuilding but had enough to cover what people wanted to withdraw. My guess is now they do not have enough to cover the expected withdrawals and would need to 'invest' real money into bitcoinica to re-start it.