I've been checking back about once a year to see if GC3 was ever announced/released. Given Stardock's track record (how they handled the Elemental series) and history (I used OS/2 from 2.0 up through OS/2 Warp before switching to Win2000), it's one of the very few companies that I feel comfortable with pre-ordering.
I spent a lot of time in the MOO3 forums back at release, I'm hoping that Stardock paid attention to the mistakes made by the MOO3 team. Such as releasing too early and releasing in an unfinished state with a UI that didn't make sense and hid key information.
Or the mistakes made by the Civ5 team where they tossed out all of the good stuff in Civ4 and failed to learn the lessons from Civ4 (what works, what doesn't work, what players liked, what players didn't like) all because it was a new developer who wanted to put their "mark" on the franchise.
Mostly, what made me pony up was the words "addition of interstellar terrain" -- which I hope means that the galaxy will be less flat then it currently is. I have to play on "Immense" with "Dense Star Clusters" with stars less common so that 2/3 of the sectors are empty and the galaxy has a feel of topography with big empty stretches combined with dense clusters and a few isolated clusters. If the new terrain adds things like dust clouds that enforce a maximum speed as you traverse those squares and affect sensor range / weapons and other features where it is often faster to go around an obstacle rather then through it, I will say they've lived up to "addition of interstellar terrain".