Microsoft Office 2010 has over taken over 2007 as the most prevalent version in use today.
On February 27, 2013, I polled the TechRepublic membership on their current version of Microsoft Office:
According to the results, the majority of organizations have moved to Office 2010 as their primary productivity suite. It seems, despite the continued ranting over the ribbon interface seen in our forums, over 70% of the TechRepublic members are using 2010 or 2007.
The rest of the story
However, as follow up question I asked if organizations had any plans to move to Office 2013. Once again, if an organization was planning to move to a new version of Office it was going to be 2010 and not 2013. A higher percentage of respondents had no plans to make any changes to their office suite.
Office 2010 had similar poll results when it was first released, so this does not mean Office 2013 has no chance to catch on, but it does mean that Microsoft has some work to do to convince companies to continue riding the upgrade cycle.