Salesforce today announced it will acquired Radian6, for $276 million in cash and $50 million in stock, according to a press release issued today. Radian6 is a social-media monitoring platform that lets business clients watch, analyze, and engage in social-media conversations about their business and competitors. The deal is expected to close at the end of July.

The acquisition will bolster Salesforce's existing business tools, in particular the private social-media platform, Chatter, which became publicly available earlier this year. Radian will let Chatter users, who are on a private network, see what conversations are occurring in the public sphere within the context of their business exchanges. Radian6 scours information from Facebook, Twitter, YouTube, blogs, and online communities to find instances of company names, brands, products, and services. By amassing the data into one place, decision makers can gain better insight into what's being said about their businesses and brands.

Radian6, which was founded in 2006 by a company of the same name, offers more business-specific information and dashboard tools than many other social-media analytics providers. In addition to monitoring what's said online by the public about pa business and its products, Radian6 provides a monitoring platform that can track what's being said about competitors; indicate whether public opinion is overall positive, negative, or neutral; and see which social media sites are most active for discussion of a particular product or brand. It also includes an "engagement platform" designed to help company representatives connect with online communities. Radian6 is already widely used by more than half of Fortune 100 companies, including Dell, Kodak, and UPS.

A number of new features and enhancements for Radian6 will be revealed at the first-ever Radian6 User Conference, called Social 2011, scheduled to take place in Boston on April 7 and 8.