Apple isn't thrilled about Amazon using the word "Appstore" in their app store. Apple was granted a trademark for "App Store", and apparently to them, the differences are too close and constitute infringement. The drama gets even more complicated by the fact that Microsoft has challenged Apple's registration of the term "App Store" entirely, and is taking it before an appeals board. None of the companies involved have issued any comments on the matter.
Hmmm... I wonder if I could trademark the phrase, "That's cheesy."