No. That's something different. The * on the buy side means you cannot open a long position at that point in time. This means the dollar reserves are low, because when you open a long position, you are essentially buying bitcoins, and betting the price will go up. Shorting is when you "borrow" the bitcoins, sell them, and then buy them back at a later (lower) price. So if there is a * on the sell side (no btc) you can't open a short position.
Liquidation (zhoutonged as the folks in speculation like to call it) is when the price moves too far and you get a margin call. This means you were long and wrong, the price dropped, you get closed out and lose your original investment. In real markets you would get a chance to liquidate it yourself, or increase your margins with more funds. Zhou can't do that because of the anonymity of bitcoin, so he autocloses the position at this point.
Leverage is the main reason for the *, bitcoinica provides up to 10x leverage (scaling depending on how much your investment is). * on buy means a lot of people are long, or a few have a lot of leverage and are susceptible to volatility.