Apparently one of secrets of driving a kart in the wet is to physically move your weight around in the kart in order to unweight the inside rear wheel.
The kart has a natural tendency to understeer as the rear axle doesn't have a diff, and will tend to resist attempts to turn. In the dry there's usually enough grip at the front to unweight the rear (the steering geometry is set up to actually lift the inside rear wheel once you're turned in). In the wet though you actually need to lean forward when turning in to get as much weight over the front as possible. You can then start to lean back again to quell oversteer once past the apex.
This technique actually gives an advantage in the dry too! Not tried it in my road car though.
Hmm .. do you think I took the karting on Graham's stag weekend a bit too seriously? ;o) And can you tell I'm bored at work?
I'll have to remember that for next time I'm karting in the wet.
Not sure about quelling the oversteer though, the last couple of laps I was having too much fun kicking the back end out deliberately and catching it with some opposite lock :-D