Of the 17.5 million shares being released today, 1 million belong to former employees. A group of people (number unspecified) likely to be eager to get out at the first possible moment.
5.2 million belong to 16 former owners of websites that Homeaway purchased. Not as strongly motivated to get out as the first group, and with an average ownership of 325,000 shares needing to take their time selling off to avoid driving down the price, but probably without much loyalty.
8.6 million belong to three venture capital firms (one of them Google's investment arm). More likely to take their time.