Microsoft announced today plans to buy Skype Technologies SA for $8.5 billion in cash. The agreement has been approved by the boards of directors of both companies.

[ad#Google Adsense 300×250 in story]Skype is the popular teleconferencing software that enables users across multiple platforms (including Mac OS X and iOS) to communicate with one another, either in point-to-point or group chats. The company is based in Luxembourg, and its investor group was led by Silver Lake.

Microsoft said that Skype will support Microsoft devices including Xbox and Kinect, Windows Phone and others, and Microsoft will connect Skype with Linc, Outlook, Xbox Live and other communities.

“Microsoft will continue to invest in and support Skype clients on non-Microsoft platforms,” said the company in a statement.

Skype CEO Tom Bates becomes President of the new Microsoft Skype Division, and will report to Microsoft CEO Steve Ballmer.