For most people when Microsoft push key software out to developers for testing it would normally mean nothing. However, on this occasion Microsoft have also chosen a few select individuals to use the software and provide the company with feedback based on the user experience. Naturally, the users have had to sign a non disclosure agreement, so not much is going to get out on the product named Microsoft Office 15, but in reality is just Windows Office 2012 or possible 2013.
According to PJ Hough CVP of Development, Microsoft Office Division, he said in posting on the Office Exec blog;
This morning, we reached an important development milestone: the beginning of the “Office 15” Technical Preview Program. Office 15 is the codename for the next generation of the Microsoft Office products and services, and the Technical Preview is the first time we share our work with a select group of customers under non-disclosure agreements. These customers play a key role in our development process by testing early builds and providing feedback, which we incorporate into the final release.
Source [IT Pro Portal]