howto: file system activity to stop xscreensaver running?

[Nano Nano <40101.nospam@comcast.net>]

I have Gaim set to go autoaway after 2 minutes of inactivity,
and my xscreensaver to go on after 3 minutes (I just like it like that).

I also have a camera and the motion package installed, so I trigger an 
action like create a .jpg whenever anything moves in front of the 
camera.

I'd like to write a script so that whenever such a file is created, the 
"xscreensaver inactivity" timer is reset, so that when I'm sitting in my 
chair reading a web page not moving the mouse, Gaim won't go autoaway 
nor will xscreensaver activate.

Can I do that?