We learned a bit of interesting info, apparently Star Trek Online's Klingon faction will be Player-vs-Player only when the game launches in February.  Klingons also have their own special rank progression with different ship types available to different ranks.  Check out the info below.

Klingon gameplay is one of Star Trek Online’s most unique features. It exists as an additional advancement path for players, and offers different gameplay options to players more interested in player-vs.-player combat.

Players will be able to create a Klingon character after they unlock the first sector block of Federation content, about five hours into the game. Their Klingon character will begin at a rank approximately equal to the Federation character that unlocked the content.

Klingon Captains have the same number of skills available as their Federation counterparts, including the same professions. Your Klingon Captain can be a Science, Engineering or Tactical officer. However, they must advance through PvP, as they will not have access to the same amount of player-vs.-environment content as Federation players at launch.

That’s not to say Klingons won’t be a robust faction. While they are PvP-focused, PvP in Star Trek Online is something we designed from the ground up to be a viable advancement path, meaning both Klingon and Federation players can reach a rank of Admiral solely through PvP. Players can engage in team vs. team, Federation vs. Klingon, Klingon vs. Klingon and Federation vs. Federation combat. What’s more, certain PvP maps will have PvE objectives over which opposing players can struggle. (source Star Trek Online)

Klingon rank progression (with available ships)

Warrior
B’rel Bird of Prey – capable of cloaking in combat.

Lieutenant
Bird of Prey Mk. 1 – capable of cloaking in combat.

Lieutenant Commander
Bird of Prey Mk. 2 – capable of cloaking in combat.
Raptor Mk. 1 – similar to Federation Escorts.

Commander
Bird of Prey Mk. 3 – capable of cloaking in combat.
Raptor Mk. 2.
Battle Cruiser Mk. 1 – similar to Federation Cruisers, but feature more forward-facing guns.

Captain
Bird of Prey Mk. 4 – capable of cloaking in combat.
Raptor Mk. 3.
Battle Cruiser Mk. 2.

General
Bird of Prey Mk. 5 – capable of cloaking in combat.
Raptor Mk. 4.
Battle Cruiser Mk. 3
Carrier – a massive ship with multiple hangar bays capable of launching several smaller fighters.

Read the full article here.