fn key not working on MacBook?

What are you trying to do with it that's not working? (In other words, how have you determined that it's broken?) You have the 2.2Ghz Macbook, so I'm assuming you've got the new keyboard layout (Where Expose is launched with F3, Dashboard with F4, volume keys over on the right, etc).

Hit Fn+F4. If the dashboard does NOT come up, your function key is not broken. (If you don't have the new keyboard layout, hit Fn+F12 instead.)

Does the function key on the MacBook work correctly in OS X?

I'm having the same problem, I think. My fn key does work in Windows XP, since the function keys (f1 - f10) act differently depending on whether I'm holding fn or not. However, other advertised key strokes don't work. Specifically, fn + delete acts like backspace (not windows delete). Similarly, fn + left is not home, nor is fn + right the same as end.

My current solution is to use http://www.autohotkey.com/ as has been mentioned elsewhere on the forum. I am using the script:

#Backspace::Send {Delete}
#Left::Send {Home}

to map command-delete to (in place) delete, and command-left to home.

For the record, my MacBook was purchased in mid February, before the very recent new rollout. I'm running XP with service pack 2, and the install is fresh as of today. I've installed the drivers that came with OS X, and have also tried reinstalling the keyboard drivers. I have updated my keyboard firmware, but I still have issues with keystrokes occasionally being lost when I switch points of focus. This information is provided to help people find a pattern as to what causing the problem.