Are paladins going to be nerfed in cataclysm? WOW(world of warcraft)?

so I've been watching a few cataclysm beta's of 85 paladins and their dps, and i realised how much their dps has been reduced compared to other melee cl', could it be that the numbers haven't been finalised or the gear was poor? My second question was what PTR stands for. Any answers would be great.