Crowd-sourced local business review site Yelp has backed out of a $550 million acquisition by Google that was thought to be almost certain just days ago. Michael Arrington, writing on TechCrunch, is uncertain as to why the deal fell apart, but surmises that “someone” came up with a counteroffer for a "strategic deal" that gave CEO Jeremy Stoppleman “the confidence to say no.” But just who that is—“Apple, Microsoft, etc.”—remains a mystery. (More Google Yelp stories.)