Google's market capitalisation has risen by $16bn since the launch of Google+

"How much is social worth to Google? Investors added $20 billion to Google’s market cap the first week after the launch of Google+ on June 28. A Morgan Stanley downgrade on Friday, brought the total down to $15.8 billion because of doubts whether Google will indeed be able to capitalize on new products such as Google+. But somewhere in between there, give or take a few billion, is how much more the market thinks Google is worth than before the launch of Google+.
On June 27 (the day before the announcement), the stock closed at $482.80. It rose to a high of $546.60 on July 7, for a $20.6 billion gain to its market cap (with 322.25 million shares outstanding). Then the stock dropped to $532 at Friday’s close.
Of course there are other factors at play here (the health of Google’s core search business, the overall market, etc.). In the past week, however, the most important new event for Google was it’s latest foray into social. And even though Google+ is still in a limited beta, the market is already rewarding the serious focus on social that it represents."
Source:  Techcrunch, 10th July 2011