Microsoft recently announced a customer preview for the next version of Office, which is to be named Office 2013 when it launched next year. Today, via unnamed sources, information has leaked regarding upgrade options for those who want to run Office 2013 when it launches.
According to the report, there will be an upgrade offer, just like what Microsoft is doing with Windows. The upgrade offer will begin on October 19th 2012 and end April 30th 2013. Those who purchase Office 2010 within that time frame will be able to purchase Office 2013 at a cheaper price.
From the first screenshot above, you can see that those who purchase one of the products throughout the offer period, will be able to upgrade to 2013 for free.