I recently read that Facebook is pushing out the IPO date to next year. While I'm sure there are a multitude of reasons they might push it out, I'm curious to know what people believe to be the primary reason. Is it the lack of interest in their stock? Is it possibly that they can reach a higher valuation with new features that they are about to release? Possibly, wait for the market to settle a little bit more before jumping in?

While the Facebook example is interesting and current, I am more interested in the thought process that companies go through in timing the IPO? What are the soft and hard measures that are used when deciding the timeline?