Druids are awesome at PvP. Their healing in tree is unmatched, and druids all in all are extremely hard to kill. I have done some research on the EJ forums and have come up with a feral druid PvP spec.
In order for you to be good at feral pvp though, you have to know a few things. Always use shred. This attack will do major damage, and when combined with mangle, this will pack one heck of a punch. Another thing is that you want to have Savage roar up because it increases your damage by 30 % for x seconds depending on how many combo points you used.
There is a lot more information on the EJ forums. Be sure to look there before you get all crazy in pvp!