Microsoft's next-generation Office suite reached the Technical Preview Program stage today. The software giant revealed it is sharing its work with a small number of third-party customers under a non-disclosure agreement (NDA). Preview bits for the next release of Office, codenamed Office 15, will be made available to these customers to test and provide feedback for a final release, expected later this year.

Microsoft isn't making the code available broadly just yet, but a public beta will arrive in the summer. There's also no word on what features we can expect in Office 15. "I can tell you Office 15 is the most ambitious undertaking yet for the Office Division," said Microsoft's CVP of development, PJ Hough, hinting that the company is preparing big changes for its productivity suite. Microsoft is planning to update all of its cloud services, servers, mobile, and PC clients for Office 15, and the company will share more information during the public beta phase in summer. We previously heard that Microsoft was planning a preview for late January, and we're expecting a lot of Metro changes in the applications but not a full overhaul for the Windows 8 timeframe. With a technical preview underway, there's bound to be leaks that will provide a glimpse at the future of Office before summertime.