I've had screen protectors on for a year but then had some issues with the screen not responding to touches, when I removed the protector the issues vanished. I've now decided to go permanently 'naked' as I've had my N900 for over a year now and I expect to keep it another year at least as my main phone - If I get a few scratches and decide to keep it a third year, I'll buy a new front screen! and...I've cut my nails :-)

Dan

p.s I've found a big improvement in the screens clarity and responsiveness without the protector.