Forget the iPhone. This year was all about Android. Google's mobile operating system became the most popular platform in the U.S. -- this fall 44% of smartphones sold were Androids, vs. iPhone's 23% -- by adding 200,000 users a day, a pace that should take it to a half-billion handsets by 2015. Having all but monopolized the search business, Google is continuing its push into social media (despite the utter embarrassment of Buzz). In the past few months the company has purchased five social-networking companies -- including the gaming site Slide -- and invested big in Zynga.