One more thing....the most common cause for a leaky thermostat housing is a leaky valve cover gasket!
The oil will seep out and down the side of the block. It gets in between the block and the housing and hits the rubber O-ring, causing it to swell. Then the swelling causes the plastic area around the O-ring to crack and cause a leak.
Not saying you have to do this as well, but it would be a good idea to look for evidence of this happening. Keep it wiped down and if you think this is your cause, think about replacing the valve cover gasket....its fairly cheap and easy to do.
..:: sleestak ::..
"Our mother of blessed accelleration, dont fail us now!" -- Elwood Blues