I spilled about an tablespoon of grease on my keyboard

As long as your keyboard it working their should not be any long term damage. I am very sure that the motherboard in the new Unibody MBP have some protection when it comes to keyboard spillage.

As you can see from the following picture provided by the good folks at ifixit. http://www.ifixit.com/Guide/Repair/MacBook-Pro-15-Inch-Unibody-2-53-GHz-Mid-2009 -Heat-Sink/1555/7

The motherboard is protected by a layer of plastic. And I doubt any fat can get through that. Although it would not be a bad idea to take it to the Apple store and pay a little to have it cleaned out. iFixit has some good directions on how to remove the logic-board.

But I would not worry too much.

I never understand why people feel the need to eat and drink anywhere near a laptop. My water is always at the opposite end of the desk, and if I need a drink I move to get it. I don't know how many portable macs I've seen ruined by being careless. Consider yourself lucky, and I hope you've learned a valuable lesson.

TBF: You may have been lucky enough not to cripple your MBP immediately with your spill, but a spill such as you describe will have left obvious traces if you ever need to take your machine in for a repair of any kind. And as soon as evidence of the spill is found, any chance of the necessary repairs being performed under warranty will be gone.

Taking the machine in now to be cleaned and have the greasy parts replaced will be expensive, but doing so may save whatever remains of your warranty. For a price, Apple will restore the machine to like-new condition, and at the very least, you will then have a 90-day repair warranty on it. If you have significantly more time than that remaining on your original one-year warranty, and especially if you've bought the extended AppleCare Protection Plan, it would probably be worth taking the machine in to a Genius Bar for a look-over. Ask whether, if you have Apple clean and repair the machine now, your new-computer warranty and AppleCare plan will be reinstated afterward or whether all you'll have is the short repair warranty from now on. If the spill will negate your warranty and AppleCare even if you have Apple clean it, then the cleaning probably isn't worth paying for. But if paying for the cleaning will get your warranty and AppleCare reinstated, it may be worth doing.

I agree with Andrew. I never eat when I am using my MBP. It's an expensive and finely tuned machine and I don't want to get grease, crumbs and such down into the keyboard and on the keys or (God forbid) down into the inside of the notebook. I also generally keep any drink on a separate lower table so that there is not even a chance that I could spill it onto the notebook.