This one is the second release candidate, and is 7.0, unless some fairly critical bug or other such issue comes to our attention over the rest of the weekend.
The main thing was to fix a bug that could let the Special Forces attack your planets (by choosing one of them as a "staging point", heh).
Also fixed a couple exploits, one old, one new.
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.