If you want to not allow border hopping you must have WorldGuard Events installed.
Features
Combat tagging timer.
If a player disconnects while his timer isn't 0 he dies.
When you die your timer resets.
In combat chat messages.
Config file to configure messages and time in combat.
Support with LifeSteal SMP Plugin. (Will give a heart to the tagger if someone combat logged and will make tagged lose a heart. Is configurable in the config file)
Banning commands while in combat. (configurable in the config file)
Newbie protection can be set on / off in the config and decided on how long the protection lasts.
Can make it so players can't border hop while in combat. Requires WorldGuard Events.