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It will probably corrode the internal components over time, there isn't much you can do.
 
First off when you spill water on your computer you should immediately disconnect all power connections (don't even wait for the computer to shutdown). Then you should open it up as much as you can to let it air dry. Then wait a minimum of two days before even turning it on to test if it is all right. Though you could wait less time if you completely disassemble the computer including motherboard removal as you can then survey every component for the presence of water.

Luckily none of the water got on your motherboard. But in all likelihood the keyboard is ruined from short circuiting. I would get a replacement keyboard on eBay as that is usually the cheapest place for OEM replacement parts. You can find the apple part number for your keyboard on ifixit.com or applepalace.com.
 
The iBook G4 has metal shielding protecting the Mobo. But it can still get through. I recommend you remove the logic board and put it in a bowl of dry rice to remove all moisture.
 
Chances are you've shorted out specific circuits on the keyboard. I spilled water on my Apple Pro keyboard and after cracking the keyboard open I could see that by using it again too early, I'd ruined half the keys. Learnt the hard way I guess :eek:
 
I would recommend putting the mobo through an ultrasonic cleaner with the proper chemicals, but man. that ibook is such a piece of **** when it comes to removing the mobo. Even the hard drive. For me, it's not worth the time or effort. If it's sentimental, then maybe it will be for you.
 
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