This is the biggest deal Google has ever made. We’ll see whether it gives the Web giant the resources it needs to make its Android-powered handsets even more potent competitors to Apple’s iPhone. But Motorola Mobility investors should be happy with the $40 a share offer — a 63% premium from Friday’s closing price: Billionaire Carl Icahn, who owns 11.4% of the company and had urged it to consider cash-generating options such as selling its patent portfolio, says the deal is “a great outcome for all shareholders of Motorola Mobility, especially in light of today’s markets.”

MOUNTAIN VIEW, Calif. & LIBERTYVILLE, Ill.– Google Inc. (NASDAQ: GOOG) and Motorola Mobility Holdings, Inc. (NYSE: MMI) today announced that they have entered into a definitive agreement under which Google will acquire Motorola Mobility for $40.00 per share in cash, or a total of about $12.5 billion, a premium of 63% to the closing price of Motorola Mobility shares on Friday, August 12, 2011. The transaction was unanimously approved by the boards of directors of both companies.

The acquisition of Motorola Mobility, a dedicated Android partner, will enable Google to supercharge the Android ecosystem and will enhance competition in mobile computing. Motorola Mobility will remain a licensee of Android and Android will remain open. Google will run Motorola Mobility as a separate business.

Larry Page, CEO of Google, said, “Motorola Mobility’s total commitment to Android has created a natural fit for our two companies. Together, we will create amazing user experiences that supercharge the entire Android ecosystem for the benefit of consumers, partners and developers. I look forward to welcoming Motorolans to our family of Googlers.”

Sanjay Jha, CEO of Motorola Mobility, said, “This transaction offers significant value for Motorola Mobility’s stockholders and provides compelling new opportunities for our employees, customers, and partners around the world. We have shared a productive partnership with Google to advance the Android platform, and now through this combination we will be able to do even more to innovate and deliver outstanding mobility solutions across our mobile devices and home businesses.”

Andy Rubin, Senior Vice President of Mobile at Google, said, “We expect that this combination will enable us to break new ground for the Android ecosystem. However, our vision for Android is unchanged and Google remains firmly committed to Android as an open platform and a vibrant open source community. We will continue to work with all of our valued Android partners to develop and distribute innovative Android-powered devices.”

The transaction is subject to customary closing conditions, including the receipt of regulatory approvals in the US, the European Union and other jurisdictions, and the approval of Motorola Mobility’s stockholders. The transaction is expected to close by the end of 2011 or early 2012.