Socket errors? That's weird. As long as you have updated your JBoss Cache and JGroups jars (and all other dependent jars) you shouldn't have a problem. Do you have something else bound to the same address? Perhaps a stale process?
I just figured this one out. This is a known IPV6 issue with JSE 5.
I just needed to add a preferIPv4 flag to the startup and all is good.