I actually sent Rio an e-mail about AAC support with one decent reason to support it. iTunes. Not the music store, but just the player software. It ships as the default player on all HP and Compaq branded consumer machines now, and by default rips to AAC. Consumers who buy a Rio portable music product will just expect it to work with their music, and not care how. If it doesn't support AAC, it's more likely to generate support calls, or worse, be returned to the store.

But as others said, I doubt it would make it to the empeg.