This isn't such a great thing. Bad time to have cash. Bad yields and lots of currency risk out there. Apple isn't willing to invest chunks of this into longer term investments that can yield potentially huge returns? Looks like they're happy to sit pretty with their current line at the top.
I'm pretty sure it's "cash" in the accounting sense, which is actually "cash equivalents" -- stuff you can quickly convert to cash, and that is not considered to be at risk (so this would exclude, e.g. buying stock).