You can longpress-delete playlists in the Music app.
I was unaware the playlists get moved, though this explains a side effect I'm seeing. My script wipes out a /sdcard/audio directory and reloads music and timestamp-named playlists, but the old .m3u files continue to display in the playlist screen. I have to delete them as described above. If they are getting moved this explains why the wipe doesn't clear them.
Does the auto-genned "recently added" faux playlist do anything for you?
Looking forward to other podcast-related posts.
Inspire 4G, CM7.2
TMo PAYG (no data). How I use it.