Yes - it's a bit fiddly the first time and a pair of tweezers helps a lot - I'm a messy eater and there's at least half a cheese sandwich under my keyboard...
Gently prise them off and clean up with an old soft toothbrush - then put them back...
This link will show you how...
http://www.laptoprepair101.com/laptop/2007/03/20/key-fell-off-keyboard/
Good luck...
Peccavi, January 2010