^ I normally give my board a good cleaning the moment that I notice anything under them or they respond differently than normal.
I peel off each cap, then take a small but bristly paint brush and use a combination of "sweeping" and a vacuum hose to remove any particulates. Regardless of what some might say, using a vacuum cleaner will not create a deadly ball of static electricity that will zap your computer or suck you into the 43rd dimension, so don't worry about it.
However, if you're going to use the vacuum, be careful not to dislodge any of the scissors. You will be missed, F3...
Now I'd like to know if there's any known solution for shiny keys. Yes, I know, it's natural and all, but if there's some solution in which to bathe the caps and remove any and all oils, I'm up for it! The matte keys are so much more appealing...