Certainly, the empeg can play any of the audiobooks found at http://genres.mp3.com/music/books_spoken/
Audiobooks suffer from a central problem with distribution, at least here in the States.
The audience for audiobooks is not generally large enough to support multiple distribution formats. And the largest audience for audiobooks can be targetted by supporting the tape casette format, because of the large installed base of car casette players.
Of course, this distribution model engenders a fantastically expensive pricing schedule (I don't watch it closely, but I have seen $50 casette books for abridged material) that has prevented the audiobook format from reaching more than a fringe audience.
Clearly, if ever a publishing genre could benefit from digital distribution, audiobooks could. I would certainly pay $10 to download a 600-meg audiobook file in 96k MP3 format on my broadband internet connection, so that I could listen to it in the car on my Empeg. But I am obviously not representative of the general consumer populace right now.
Presently, your best bet would be to go to an audiobook rental shop to pick up audiobooks on casette or CD format, and record them as MP3 files yourself to be stored on your Empeg.
Corby
6-Gig Blue, SN#320