Start of May 2009 and my new pets have arrived. Two small scorpions (Pandinus cavimanus).
Similar in appearance to P.imperator (Emperor Scorpion), cavimanus have similar care requirements to emperor scorpions. So high humidity (70-80%), deep substrate to allow them to burrow and warmth (warm room temp ok, but better to have a heat mat attached to one end of the tank).
My two new arrivals are about 1-2 inches long (maybe 3 inches if they flattened their tails), they have some growing to go yet. Eventually they will be similar to emperor scorpions but smaller and with dark red claws. 
They certainly like to burrow! Have been providing them with a substrate a couple of inches deep and they invariably build tunnels extending from their little artificial cave.
Every time I clean them out they very quickly set about building new tunnels. Very industrious little guys.
Thankfully they haven't tried eating each other yet (Jan 2010), so I'm relieved about that!
Lost one of the little guys recently (Mar 2010). Quite disappointed, I am quite fond of these guys. I don't think it was killed by his tank mate, no sign of any external damage. I wonder if the tank wasn't moist enough for him. I'll up it a bit/spray more frequently.
May 2010 - the 2nd one has died. Again, not sure why. The tank was humid and warm.