Salesforce announced that it is acquiring social media monitoring platform Radian6 for $276 million in cash and $50 million in stock. Founders will also get $10 million in stock and $4 million in cash.

According to Salesforce, Radian6 is used by over half of the Fortune 100, and companies like AAA, Dell, GE, Kodak, Molson Coors, Pepsico, and UPS to monitor, analyze and engage in social media conversation.

“With Radian6, salesforce.com is gaining the technology and market leader in social media monitoring,” said Salesforce CEO Marc Benioff. “We see this as a huge opportunity. Not only will this acquisition accelerate our growth, it will extend the value of all of our offerings.”

“Social media has made every business recognize the value of paying attention to the voice of the customer,” added Radian6 CEO Marcel LeBru. “Radian6′s technology is built for the new norm of customer engagement – real time, two way conversations that includes social channels. Joining the salesforce.com team will allow Radian6 to grow faster to meet the demands of our rapidly expanding customer base.”

Salesforce says the acquisition will accelerate the enterprise’s shift to “Cloud 2″ by helping companies better manage the social interactions taking place both inside and outside their companies.

Salesforce has already been utilizing Radian6. The company recently unveiled its Service Cloud 3 initiative, which involves Facebook, Twitter, and any other social network support via Radian6, so the acquisition makes a great deal of sense. Radian6 product manager Ryan Strynatka told us they were shooting for general availability by August.

The deal is expected to close in Salesforce’s fiscal second quarter ending July 31, so it sounds like it should be done in time for that. It’s already been approved by Radian6′s board of directors and stockholders.