Unlike all those previous Apple trademark disputes, this isn't a true lawsuit, and Apple hasn't sued anyone -- the city of New York has filed a trademark application for the GreeNYC apple-shaped logo with the Patent and Trademark Office, and Apple has filed its opposition to that application. That's an important part of the trademark registration process, actually: every single trademark application has to go through a 30-day opposition period during which interested third parties can raise their objections. We'd say it's pretty obvious that Apple's got an interest in other apple-shaped trademarks, so it's not particularly surprising that it's taking the first available opportunity to speak up about this one.
After the trademark applicant responds to the objection in writing (what some people have been wrongly calling NYC's "counterclaim"), the Trademark Trial and Appeals Board gathers evidence and makes a decision. We'd almost be willing to bet that never happens, though -- after all the lawyers are done strutting around and promising victory, it's likely that Apple and NYC simply come to an amicable licensing agreement. Bottom line? This is exactly how the system is supposed to work, and Apple is just protecting its billion-dollar brand as best it can -- thousands of these oppositions are filed by all sorts of companies each year. We know, not very fun at all -- anyone care to start a Jobs vs. Bloomberg slapboxing petition?
Disclaimer: Nilay's a lawyer and a formidable slapboxer, but he's not your lawyer, and none of this is legal advice or analysis.