I just came across a good article in Information week on Office 2010 vs. Google Apps. Essentially what the article says is that its comparing Apples to Oranges . And with the launch of Web Edition of Office Apps, there is very little incentive for even small Companies to shift to Google Apps. And in Large Enterprises, MS Office is so deeply ingrained in various work processes, it will be difficult to dislodge it with Google Apps. So very clearly MS Office has nothing to fear from Google Apps which is nothing more than a minor irritant.
with warm regards
Microsoft Most Valuable Professional