F9 darkens screen

[J]

On Mon, Dec 6, 2010 at 19:54, Glenn Holmer <shadowm at lyonlabs.org> wrote:
> I have an unusual issue: lately, when I press F9, instead of whatever
> that should mean in the focused window, the entire screen darkens.
> Doesn't turn black, just darkens somewhat. Just did it and I can still
> type into this window. I don't see anything in my keyboard shortcuts
> that would cause it. Anybody else ever seen this?

I've not seen this at all... and just tried on my laptop, in fact, I
tried every F key, and nothing at all happened.  Of course the
secondary functions all work for me (fn-F4 for sleep, fn-F5 for
wireless, etc)

Are you sure it's F9?  Do you happen to have that mapped to anything?
is it only with specific applicatons?