This is my current solution. It doesn't close XBMC but for windows users it keeps it out of the way when someone is done watching.
Under Event Ghost, I have it set to emulate the following key presses (with small wait times between each depending on your system speed).
Emulate "\"
Wait
Emulate "x"
Wait
Emulate {Win+2}
Wait
Emulate "\"
So what his does is window mode XBMC, stop video, then minimize it (Windows 2 should be replaced with whatever button you've set XBMC to teh taskbar to). last keypress does nothing
When it's minimized and it wants to be opened, the first 2 key presses do nothing, third (Win+2) will bring XBMC to foregorund and "\" will maximize it.
For some reason, I found that emulate \ does not work for this.
Under EventGhost, hit your "\" key and see what the key is under there. For me, the key was OEM5. So I replaced "\" with "{OEM5}".
Not sure how useful this will be for anyone since most run XBMC on a dedicated PC but hope it helps someone.
