Will Time Machine work with Networked NAS Drives?

I have an Airport Base Station with a USB hard drive hooked up to it. Will time machine work with that or any other type of networked drive? I have seen references to using a USB or firewire drive but with many laptops being used these days that would be very inconvenient.
If it doens't work with networked drives is it possible to use it where yo only plug it in at night or so for it to update the data on the drive?

This is a question that I too am going to be interested in knowing the answer to, but unfortunately, we won't be able to find out till Friday when people finally get their hands on Leopard.