Do you know what Wikipedia is saying about your company?
As this article about the brands called Hillary and Obama makes clear, the pages of the user-created encyclopedia see plenty of spin-doctoring and outright malice ("There was the day in February when an editor replaced a photo of Hillary on her Wikipedia page with a picture of a walrus") as emotions run high.
And people do get emotional about companies. With Wikipedia entries showing up near the top of Google rankings for many firms, it makes sense to check out your own listing from time to time.
People who think about this kind of stuff suggest announcing one's presence and affiliation in the relevant article's discussion page, and attempting to influence content from that vantage point.
It's pretty easy to figure out who modifies what at the site, and you don't want to look sneaky or defensive -- or, like Microsoft, get bad PR for "doctoring" your Wikipedia page -- so that's probably good advice.
It's also another good reason not to use Wikipedia to trash your competition. Not that you would do anything like that, of course.