Microsoft is teeing up a legal battle against Apple over the trademark App Store. Microsoft says Apple can’t hold a trademark on the phrase as it is such a common phrase already in use and that any value Apple can claim is essentially secondary. (You can read the complaint here. It’s a downloadable PDF.)
Of course Apple is fighting back. Cupertino contends that the “app” in App Store stands not just for application but is also short for Apple. There’s obviously a lot more than that to this once the lawyers get involved and this will be messy before it even comes close to getting resolved. Todd Bishop has an excellent write-up on this that contains more links to more of the legal stuff that is worth reading if you’re interested in these sorts of things.