I tweeted a little while ago about Nokia recently supporting interface failover within IPSO, well it looks like Cisco's ASA Version 8 software can do it now too!

The following example creates two redundant interfaces:

asa(config)# interface redundant 1 asa(config-if)# member-interface gigabitethernet 0/0 asa(config-if)# member-interface gigabitethernet 0/1 asa(config-if)# interface redundant 2 asa(config-if)# member-interface gigabitethernet 0/2 asa(config-if)# member-interface gigabitethernet 0/3

Reference: Adding a Redundant Interface