The folks at Massively spoke to Star Trek Online Executive Producer Craig Zinkievich at this year's Game Developers Conference and managed to score some tasty information: new playable factions will be coming to Star Trek Online this year.
So what factions are coming? They aren't sure yet, though Craig does admit many of the development team are interested in introducing Romulans to the game:
There's a huge amount of the dev team right now interested in doing Romulan. I think the Borg would be really interesting as just something totally different, totally different gameplay. There are a lot of really cool mechanics, a lot of really cool things you can do there. Really, if you're in the MMO for the long haul, there are going to be a lot more playable factions, you can't stop with those two. There's Jem'Hadar, you're going to be going to the Dominion, there's Cardassians [...] so many playable factions that we can and will be releasing with the game.
Craig also dated the next major update for Star Trek Online for this July, which will be followed by yet another large update possibly around November.