This one addresses several things but mainly reworks the new expansion's Core Turret Controllers to better achieve their goal: easier distributed defense, and being more of a benefit to distributed defense than chokepoints (not trying to nerf the latter, just trying to not buff them much either).
Basically, the core turrets you can build with the new controllers won't co-exist on the same planet with lower-mark turrets of the same basic type, so you can't stack I+II+III+V turrets on a single planet, but have to choose between I+II+III (if you have II and III unlocked) or V.
On the other side, the controllers now both are more numerous and give more turrets each, and all mkII+ turrets (include core ones) cost way less m+c.
This patch also adds a "decolonize" option for when you want to abandon a planet without triggering the Shark plot (doesn't apply to other consequences of losing a planet) for situations where you're trying to capture something only for a short time (ARS on Dyson planet, etc). It's possible this enables too much cheese, but in general if you think a particular usage is too cheesy you can just not do it; either way, we'll see.
There's also fixes for a few longstanding issues with AI units getting stuck trying to attack radar-dampened units but not wanting to close far enough to actually fire, etc.
Oh, you might also notice the cool new main menu background ;)
This is a standard update that you can download through the in-game updater itself, if you already have 4.000 or later. When you launch the game, you'll see the notice of the update having been found if you're connected to the Internet at the time. If you don't have 4.000 or later, you can download that here.