The trademark was filed in the Advertising, Business and Retail Services, Computer and Software Services and Scientific Services categories.
The trademark applies to "retail store services featuring computer software provided via the Internet and other computer and electronic communication networks; retail store services featuring computer software for use on handheld mobile digital electronic devices and other consumer electronics."
The "There's an app for that," tagline plays a large role in Apple's marketing and advertising initiatives around the iPhone and all other iOS devices. The phrase has become so popular that it has permeated pop culture and become repurposed and parodied in a number of fashions. It makes sense, then, that Apple would want to trademark the phrase and prevent other businesses from profiting by the commercial use of the phrase without its consent.
[via TUAW]