Pings are more a network keep alive now, every 30 seconds a ping should be sent to check connected nodes.
Host caches are currently the weak point in the network since there are only a few.
Clients now return X-Try headers with IP's of other clients when you connect to them and they are busy or behind a superpeer.
Swarming has caused a lot of busy problems. Now people can clog the upload slots 4 times as much!