Audible, iPod and bookmarkable Audio books

[Hubs]

Friend of mine belongs to Audible this is a service that lets you download audio books . Probably the largest most popular its downside is it is hooked up with Apple it formats in apples restrictive format limiting it to be played on only certain manufacturers mp3 players. The good thing about their encoding is it lets you bookmark where you left off in the book. So it is easy to find where you left off listening to a chapter.
Does anyone know of a way to copy audio books that will split the tracks. with information like a id3 tag or something.
I was thinking of checking out a couple of audio books from my local library just to see if I would enjoy listening to audio books. Are these books recorded in mp3 files or a wav file ? If you wanted to save to a computer would you store them in one big mp3 file and what would be a good compression for audio books 64 kbs ?