Thats somewhat silly as mp3's can be attack vectors, though I don't know if this is a problem in the wild.

http://www.eweek.com/c/a/Security/GMs-OnStar-Ford-Sync-MP3-B...

I tend to run clam-av on file servers and mail gateways for the obvious reasons. I like the software, it works quite well. I'm going to have to look into the mp3 block though, this just seems like a bad idea.