Yes, you can wash your Apple / Mac keyboard in the dishwasher. I’ve done it with other PC keyboards before. This is the best way to wash a Mac keyboard. Below is a video that talks about it. When done, you’ll have a brand new looking Mac keyboard.
Make sure you let it dry 24 hours (or longer) after you wash it. So either have a back up keyboard or do it on a Friday night, take Saturday off (go outside and play!) and then you can use it again on Sunday or Monday.
source: How to wash your Apple keyboard in the dishwasher (www.wonderhowto.com)