I do hope that in cata Hunters are able to have a bit more flexibility in what the gem. For example most casters gem any combination of SP/Haste/Hit etc where as Hunters for the better part of WoLK have been forced to gem either straight ArP/Agi or Agi/Crit for Socket bonuses.
Hopfully in cata we might see Haste/Agi/Crit gemming combinations becoming popular, rather than the boring old straight agi or ArP.
Well, there won't be any ArP gemming cuz it doesn't exist for gems come Cata. Hunters will be gemming Agi/Crit/Haste/Mastery. So there should be plenty of options.
Most casters gem either pure spell power or spell power/haste in every socket. Most melee gem pure strength, armor penetration, or attack power. Hunters aren't some special snowflake in gemming for their best stat. :/