at our work, we have two data center connected via T1 wan link, and a single default-gw, so what we did was add another T1 at the other data center with load balanced the new T1 and PIX to the main data center's PIX. so that when the main wan link goes out, it would be re-routed to the pix-to-pix tunnel from our other T1

--w0rm3y