Over the years, there have been many software firms and other companies that have tried to release an office productivity software suite to battle Microsoft's dominating Office application. So far, none has been successful in putting a dent in Office's market share.

Microsoft has for a long time offered trade-up programs free of charge on its Windows operating systems when a new version is around the corner. Microsoft does this to prevent consumers from simply not buying computers and waiting for the new OS to come on the market. Microsoft apparently has something similar in mind for those who buy Office 2007 since Office 2010 is on the horizon.

Microsoft showed off a release candidate of Office 2010 to members of the Technology Adoption Program early this month and the official release is expected to hit the market in June of this year.

A bit of information on the Office 2007 to 2010 upgrade program was accidentally posted to the web yesterday and was then quickly taken down. Ars Technica was fast enough to grab screenshots of the post before it was removed -- Google cached the post as well.

The program is not officially announced by Microsoft, so it is offering no official comment. The accidental post notes that Office 2007 buyers that get the software with a new PC or purchase the software along between March 5, 2010 and September 30, 2010 will get a free upgrade to an equivalent version of Office 2010.

The buyer has to install and activate the Office 2007 software by September 30, 2010 and request the Office 2010 upgrade by October 31, 2010 to qualify. The Office 2010 update is expected to be offered via download, though Microsoft typically will send out discs with the software for the cost of shipping and handling.