The lesson to be learned from the Facebook IPO is to not buy an IPO (no matter what the company) in a negative market environment.
The red dots on the chart below are the indicator I use to determine market direction. It measures the breadth of the market and is the best measure of mass market psychology.
Since most stocks move with the general market, there is a saying among traders: "Buy when the market tells you, sell when the stock tells you." Or in FB's case, "Sell short when the market tells you, cover your short when the stock tells you."
Had Facebook issued their IPO in the period just after the green horizontal line on the chart it would have a different, more positive story for the stock (note how it rebounded from it's initial drop during the time the red dots rose).
However, FB has continues to decline with each renewed downturn in the general markt (the red horizontal lines on the chart) and there is no bottom in sight for the stock.