serial line for heartbeat

It seems FailSafe requires 2 network cards just for the
control network.

It would be great to be able to use a serial connection
for heartbeats and one ethernet connection. Like the
"heartbeat" package does it. I'm sure it would be a popular
option since it saves one network card.

I spend a lot of time studing the guides for FailSafe but
finally I have to go with "heartbeat" since I only have
2 network cards on each of my servers.

Thanks,
Marcus