Full patch notes here http://fractalsoftworks.com/forum/index.php?topic=13445.0 pretty lengthy.

Starsector version 0.9a is now out! Here are some of the new things you can do in this release:
Establish colonies! Build up industrial production to make a profit, improve your colonies, and protect them from many dangers
Visit a portside bar to find missions and other opportunities
Fight alongside – or against – massive orbital stations
Create your own faction and set up its military doctrine
Find blueprints and use them to let your colonies produce ships, weapons, and fighters
Face enemy ships with dynamically generated weapon loadouts
Discover new dangers and derelicts on the fringes of the Sector
Explore planetary ruins
Raid core worlds for plunder or to disrupt your competition
In addition, there are a ton of UI improvements, improvements to ship AI, combat balance changes, and all sorts of miscellaneous fixes, improvements, and bits of new content.