Everyone is freaking out about a new feature in the 1.7 tree, Local Peer Discovery. It uses multicast traffic to try to find geographically-close peers in order to speed up your transfers. The multicast block of addresses (224.0.0.0 - 239.255.255.255) is normally blocked by routers/firewalls/etc, leading to alert popups, leading to OMGWTFMPAABACKDOOR! calls.
