Take the carpet to the Tate Modern and enter it for the Turner prize? ;-)
If you want a serious answer:
Mop up as much as you can with kitchen towels. If it's the type of carpet which doesn't mind a bit of water, get a big bucket & sponge and mop it over to try to get some more of the milk out. Then head to your nearest branch of Pets at Home to buy a bottle of this stuff: http://www.simplesolution.com/products_uk/stai n&odor.htm
(It'll kill any stale milk smells).
Get that maid back in right away, wearing her sexy maid costume and stockings and garter. And make her get down on all fours and lap up the milk like a cat. And she should miaow while she's at it.
Leave the cat there, place an empty saucer nearby. When the maid comes in, blame the cat and tell her the carpet needs to be washed right away coz the smell is making you sick ... tell her to put that no-good cat out as well
I was just going to ask the same question as dotty, very disturbed by romeo's replies but think Wardy's idea is bloody genius, except you'd have to go for Butterscotch ;)