Leopard & screensaver & selective lock

I use to take my MacBook Pro with me a lot, and to connect to a lot of
different wireless networks, much like most everyone else here, I
presume. I have the machine configured to ask for my password on coming
back from the screensaver. Which is what I want - usually. However,
when I'm at home I find it more than a little annoying to, quite
unnecessarily, having to type in my password all the time. Yes, I can
manually disable the locking, but I'm wondering if there's any way of
teaching the machine to lock the screen on coming back from the saver if
and only if it's not connected to my home network (checking for, say,
SSID would be OK for my needs).

I'm running the latest incarnation of Leopard.

Any ideas?

Thanks,
Tom