Detect when a session times out and execute a function

[eluser]funkmyer[/eluser]
precisely -- I'm aware that all the session handling is automated so I'm trying to find a hook/event to tie into when the session garbage collection runs. Thanks guys, all your feedback and thoughts are greatly appreciated!

I'm going to do something along the lines of sandworm's recommendation, so I guess my last lingering question is if anyone knows of any hooks/events/triggers etc.. for the automated session garbage collection to signal one of my own functions to run some additional operations. Although thinking about it, that possibly wouldn't work anyways as by the time I got the "signal" that session garbage collection has started, and the data I need may already be gone...der

Thanks.