The most important thing is DO NOT TURN IT ON. Leave it off, and set it to dry - either with rice as people have suggested, or just on a hot ventilated place, I would say for at least 2-3 days before even trying to turn it on.
If you spilled only water there is a good chance it will work (if you didn't try to turn it on directly after the spill, then the chance is much lower). If it's soda, the sugar in the drink will form a sticky goo when it dries and can cause some troubles. I actually did this myself (with beer) on an old Macbook Pro, and the result was that about 5 keys on my keyboard stopped working, although otherwise it was fine.
If you spilled only water there is a good chance it will work (if you didn't try to turn it on directly after the spill, then the chance is much lower). If it's soda, the sugar in the drink will form a sticky goo when it dries and can cause some troubles. I actually did this myself (with beer) on an old Macbook Pro, and the result was that about 5 keys on my keyboard stopped working, although otherwise it was fine.