????First Yelp, now Groupon: Why hot startups -- especially those holding the key to "local" -- keep slipping through the search giant's fingers.

????While the official confirmations have yet to land (and my colleague Dan Primack is following up on Groupon CEO Andrew Mason's hopefully tongue-in-cheek offer to discuss the finer points of his affection for miniature dollhouses), it's looking like talks between Google and Groupon have fallen apart. The situation is eerily reminiscent of Google's (NASDAQ:GOOG) talks with Yelp, just about a year ago. Google, thought to be after Yelp's ground army of local sales teams, now stretching across much of the U.S. and Canada and some European countries, either got cold feet, or got a cold shoulder from CEO Jeremy Stoppelman, and returned him the favor.

????Maybe it's something about the holiday season that leaves Eric Schmidt wishing the company had a killer local business offering up its sleeve, but whatever the case, that marks two failed acquisitions of social or local-oriented startups. (His successful 2005 acquisition of Dennis Crowley's Foursquare precursor, Dodgeball, came at a different time in tech, and anyway, Google ended up shutting it down and alienating Crowley.)

????It's worth noting that Yelp was, according to reports, in talks to be bought for three quarters of a billion dollars. The bidding for Groupon, a site by all accounts offering far less sophisticated technology, was said to have reached $6 billion, including various retention incentives for Mason and other top executives. Social and local are not getting any less valuable.

????Groupon is almost certainly set to clear far more cash in a year than Yelp seems to be, thanks to the fact that Groupon hit upon a real revenue stream and incentive for both users and businesses to pay for its services, it is now being said to have a projected $2 billion revenue run rate for 2011. But Yelp's database and user community would seem to have even greater implicit value to Google, even if that value is currently locked up by the site's emphasis on reviews rather than transactions. (That's fixable, by the way: Isn't Yelp the perfect place for group coupons?)

????While the courting continues -- or doesn't -- it's hard not to wonder how Google got itself into this position. Here's the dominant company of the Internet age, the ultimate traffic generator that should cause any of the companies it is talking to to see massive growth and to make the founders wildly rich. But, it seems, the issue now is not what Google's willing to spend, it's about what kind of company it has become -- and whether this founders believe this is the caretaker that will help their babies grow.

????While Google Ads revolutionized the way companies of all sizes connect to customers, when you think about the really big companies that rely on Google for traffic, where is the profit? YouTube, which Google acquired in 2006, will finally be profitable on $700 million in revenue this year. (Maybe.) Media organizations, most prominently the New York Times, that rely on Google's search results for their traffic are in the same boat as YouTube: They have experienced huge search-based traffic growth, but poor profitability, especially, as Felix Salmon notes in his dissection of Gawker's new business model, with CPM rates looking like a "race to the bottom."

????Now think about the companies that have emerged on the back of Facebook's social discovery platform: Zynga and Groupon, to name the two biggest, are wildly profitable. While those companies were set up to monetize traffic in a way that YouTube and the New York Times (NYSE:NYT) clearly were not, they benefitted from the power of Facebook's social graph and, as Fortune's Kevin Kelleher recently wrote, its evolution of search advertising into targeted and highly effective social advertising. [See: "How Facebook fixed the social advertising problem."]