Suggestions are very much in order.
In order to do that we need a way to force a failover, which should be called by an external monitor such as mon or netsaint. Thus we can use an external program to monitor an ethernet link or any other resource and force a failover in the case of failure. I'm pretty sure it can be done without breaking heartbeat's semantics. And, of course, this way we could cover node and resource crash. Well, if it sounds good to you, please let me know.