There are currently only two major types of vessels used for combat: the Battlestar and the Gunstar, but thanks to recent advances in ship design and weaponry, a new ship is taking shape, the Cobra.
The Cobra is a smaller ship, it has new superlative armor, and new positronic computer systems that allow it to stay relatively small. The normal crew size is only 35. The ship is part of a new effort to develop smaller, heavy fighters to help combat the new threats to the Colonial government.
There are other ships waiting to be built. The Sagitaran Science Academy is currently working on a new class of vipers to replace the aging and less effective Colonial vipers that service the fleet. The new class of vipers will incorporate new phaser and shielding technology.