In fact, Steve Jobs himself has been caught using "app store" in a generic sense. Amazon.com
All of this may be true, but it only makes Microsoft look hypocritical. Claiming genericness is convenient when the trademark claim belongs to someone else, but has everybody forgotten that this is the company that trademarked the term "Windows"? I suppose Jobs could point out the last time Steve Ballmer let a little sunshine into his living room and declare the Windows trademark unsupportable.
The solution to Microsoft's problem seems obvious: Come up with a snappy new name for your app store and let users refer to it any way they like. Android users may talk about their app stores, but the official Google
Microsoft's lawyers have enough work already. Ballmer should call his attack dogs off and save some legal fees. There's no point to this complaint.
The comments box is wide open for your view on the app store situation. The Fool might trademark "comments box" if this nonsense continues.