Our Early Access review of Galactic Civilizations III was quite positive overall, although it noted that "there's still a long way to go" before its release next year, in large part because it was missing major features like diplomacy and trade. Well, they've hopefully fixed that for you. The Beta 2 version released today brings both to the game, along with a new race and a pile of other features and fixes.
The Beta 2 update will install automatically through Steam, after which players will be able to enter into diplomatic relations with other races, establish trade routes to other planets and trade credits, tech, ships, and other resources, set fleet rally points, and earn victory through a number of new conditions. The United Planets, essentially an intergalactic version of the United Nations, is now in the game, as are the Krynn, who will bring a more aggressive approach to their relations with others than they've previously been known for.
On the less-spectacular-but-still-significant side of the coin, the new beta adds a number of interface changes, punches up the AI, fixes a bunch of bugs, and makes "too many balance changes to mention."
The full list of additions and changes in the Beta 2 release is up on the Galactic Civilizations III forum. The game is currently available as an Early Access release on Steam, and is slated for a full launch in early 2015.