Qaz, would you consider installing this on the server?
http://www.minecraftforum.net/topic/493077-11-redstone-torch-burnout-fix-ssp-smp/I've been noticing since 1.1 that redstone torches are being more finiky than ever. I'm down at the blaze xp farm at the moment but the torches are burning out after a single use for no particular reason (when before 1.1 it worked perfect).
Note that none of the torches are receiving any fast pulses, so they should *not* be burning out, it's definitely a bug (as described in that thread I linked anyway)
I'm not that familar with SMP mods though, so not sure whether just the server needs it or if players have to download it as well, and in that case it would be fairly pointless.
So yeh for anyone that's wanting to use the xp farm, it's broken for the moment until the stars re-align or something.