GameSpot talks about the upcoming Mercenaries expansion, and has a video showing off some ship classes gameplay in Galactic Civilizations III.
"The game's new mercenary system stems from a pool of mercenaries, each of which costs a certain amount of currency to obtain. Some grant combat buffs for units in select areas, while others afford economy boosts and increase movement by 50 percent, among other things."
Read more: http://www.gamespot.com/articles/new-galactic-civilizations-3-expansion-announced-w/1100-6434223/