3.x...
that s just ancient.. it s not even supported by MySQL devs anymore...and when that happens you should consider upgrading
i think 4.1 should work, but if you have to upgrade anyways, i d go to 5.0 (not 5.1), but that s just me... 4.1 isn't bad, but since the 6.0 is currently is allready in alpha stage, and 4.1 support will most likely be dropped when 6.0 goes final, i d skip the 4.x branch
edit: as for which version is 'required', since anope currently does not require any constraints of any kind it could do with 4.1, but usually newer versions mean more bugfixes so it s always good to stay up-to-date
[Edited on 20-6-2007 by Viper]
[Edited on 20-6-2007 by Viper]