Cryptic Studios has published an FAQ which answers many common inquiries about their vision for Star Trek Online
When does the game take place?
Approximately 30 years after the events in Star Trek Nemesis. The game starts in 2409. Technology has advanced and the galaxy is a much more volatile place.
What races will we be able to play?
The plan is Human, Vulcan, Andorian, Klingon, Orion, Gorn, and several others. You will also be able to create your own race with its own custom look and attributes.
Will everyone be the Captain of their own ship?
Yes, but you will have to earn the responsibility and skill to command larger and more powerful vessels. Remember, in Star Trek as well as naval tradition, whoever commands the ship is the "Captain," even if it is not your current rank.
Read more here.