What does the iTunes "Media Kind" actually do?

"It's very useful to be able to change the media kind if you own an iPod, as you get different features for audiobooks and podcasts (2x speed, 1/2 speed, skip back 30s).

I would also consider the searching, filtering and library categorisation as a feature. I think it is nicer to see the Hitchhiker's Guide as one book icon, with the chapters organised within that, rather than having this lumped in with the rest of my music."