id3ed is an ID3 tag editor for mp3 files. You can set tags interactively or from the command line, or a combination of both. id3ed can set genre by name or number. You can also remove or view tags.
Perhaps. I have nothing against the idea, just haven't found the time to implement it myself. (yet?) Patches welcome :)
Update 20010916: I have begun tentative work on id3ed2 which will support both id3v1 and v2. Currently I'm experimenting with the pyid3 module.
Update 20030109: obviously, that didn't work out. Unfortunatly the pyid3 module seems to be dead, so no v2 for now.