When Apple trademarked the term "App Store" nobody thought much of it.  Smartphone applications at the time were a niche market either highly targeted at small groups of professionals, or were tools used by handset makers/carriers to sell their devices.  In months Apple transformed the mobile applications industry into a huge market that lured personal computer developers into the world of ultra-mobile computing.  All of a sudden, the term "App Store" was a household name.

Now "App Store" is a somewhat generic term.  Google, the market's biggest player has long remained silent on this issue.  But in recent months Microsoft, in the midst of a major smartphone push, decided to press the point, filing suit against Apple in January, claiming the U.S. Patent and Trademark Office (USPTO) erred when granting Apple "ownership" of the term "App Store".

Now Apple's legal team has fired back in a response to Microsoft's claims.  They argue that the diversity of smartphone OS maker's various store names offers some proof that the term "App Store" is not overly generic (Google uses "Android Marketplace", Windows uses "Windows Phone Marketplace", and Palm uses the term "Palm App Catalog").  They say that Microsoft fails to prove that the term "App Store" is overly generic.

Further, they level a stinging accusation back at Microsoft.  They argue that Microsoft's ownership of the operating system trademark "Windows" is illegal.

Apple legal writes [PDF]:

Having itself faced a decades-long genericness challenge to its claimed WINDOWS mark, Microsoft should be well aware that the focus in evaluating genericness is on the mark as a whole and requires a fact-intensive assessment of the primary significance of the term to a substantial majority of the relevant public. Yet, Microsoft, missing the forest for the trees, does not base its motion on a comprehensive evaluation of how the relevant public understands the term APP STORE as a whole.

The San Jose federal court where the case was filed must now rule whether to grant a motion (instant decision) or put the case before a jury trial (prolonged court process).

Ultimately both Apple and Microsoft raise valid points.  On the one hand, the term "App Store" (with no company name included) does seem overly generic.

However, the case merely serves to illustrate the broader issue of the USPTO increasingly granting ownership of increasingly broad and generic trademark names to large companies.  In this respect, Microsoft's claims are certainly a case of the pot calling the kettle black.  Operating systems have used windows-based GUIs since before the days of Windows, and every major personal computer OS today uses a windows-driven interface.