InfoWorld posts a blog entry on Apple filing a formal complaint with US Patent and Trade Office.

Look at this logo for a moment:
If you saw it on a reusable cloth shopping bag, would you think for a moment, "Hey, that must be Apple's new iBag!"?
Apparently, Apple is worried that's the case. The above logo is actually the emblem of New York City's GreeNYC campaign, the Big Apple's move to encourage denizens and visitors to reduce pollution and greenhouse gases.
In case you can't tell, the GreeNYC logo is a combination of the infinity symbol and a green apple, the implied message being something along the lines of, "Let's keep the Big Apple green for all eternity."
Apple maintains that the GreeNYC looks too much like its own corporate logo, which, of course, looks like this (in green):
The company has gone so far as to file a formal complaint with the U.S Patent and Trade Office against the GreeNYC logo, according to Wired, claiming that it will confuse people -- and potentially tarnish Apple's good name. "Any defect, objection or fault found with [GreeNYC's] goods and services marketed under [GreeNYC's] marks would necessarily reflect upon and seriously injure the reputation which [Apple] has established for its goods and services," the claim states.

Even though this positioned as bad Apple, speaking as an ex-Apple employee and the knowing the importance of the logo. Apple needs to make reasonable efforts to defend their logo. If Apple stopped defending their logo, then they could use their rights to the logo. This may be obvious its different, but when it comes to an attorney and his legal responsibility he/she will be conservative.