Just to be clear, the bans are simply expiring after something less than ~44 hours (you can see from Davy's report on 65 and my report on herly rios). This arbitrary time is clearly not enough for most tk'ers. If you recall, the policy started out as 2 days, and that's essentially what we did for months. However, as teamkillers got more brazen (maybe from the server segregation), the mods started making these 3 and 4 day bans. Right before went back to civilian life, the typical ban was 4 days, and we generally weren't hearing further complaints about the majority of the one-timers. Exception was the real a$$wipes, for whom permanent bans was the ONLY workable action.
Of course, at that point, Zup hardcoded the bans to this temporary 40-some hour thing. This was an attempt at not having to track a ban and un-ban a person, but the result was that now mods have to track when they ban and need to re-ban, and there will be gaps since mods have real lives outside of DF.
People do TRY to get around bans by changing names and buying the game again. No one can do much about them re-buying the game, although Z seems to have taken the nuclear option by banning Richyroo's IP address and perhaps taken out an entire city block in Essex. As for the name changers, that's why I used to post player stats when I banned or muted people, and that's even more important now, since mods have to come back 40 hours later and find these players again. But if the mods ever have trouble finding a player, Detective Manfred is on the case! And these dodgers should get the permanent ban, IMO.
Manfred