It's semantics. It's cash. Not in the literal sense that they are wallpapering the headquarters with it. But it's cash from profits they've earned, that are invested in bonds and securities, just like you are I would.
>Long term marketable securities are basically those things that they would likely take a significant hit on if they had to actually convert to cash in a reasonable period of time.
Not necessarily true. Apple holds something like $15BB in Treasuries under their LTMS holdings. These are liquid (hence the label marketable). They also own a bunch on municipal bonds and corporate debt, most of which are also extremely liquid.