Midnight was only perma-banned twice IIRC. First time was ages ago. Eventually he sent Prince an email asking to come back, and got accepted. Then he was banned for 3 months (late last year to early this year). When he came back, he got banned permanently, and wasn't unbanned since.
I don't think that there should actually be such a thing as a perma ban. It should just be a max of a year. If they care enough to come back after a year, then good on em. Perhaps they changed.
@ El Nino. They are life bans unless you ask for it to be revoked. @ Ged. I disagree. To get a permaban you'd pretty much have to do a million things wrong, and there's a strong chance you'll never change.