Nobody has really publicly talked about it, but there is now code in the Notchian and CraftBukkit servers to limit connections from single IPs to once every 5 s

Nobody has really publicly talked about it, but there is now code in the Notchian and CraftBukkit servers to limit connections from single IPs to once every 5 seconds, and to disconnect slow logins by killing the thread after 30 seconds, effectively limiting the attack to 6 threads used per attacker. To actually bring down a server this way would then take 100 attackers or so. This really is just a proof of concept, after all, and not a tool which can bring down entire servers single-handedly. (At least, not anymore.)