Third in the Old Man's War series by John Scalzi...
Yay! Scalzi book!
I finally figured out one of the things I love about his books while reading this one. He assumes the reader knows things, the books are smart. I love that. There's references that you're just assumed to get. For example, in this one the planet is called Roanoke and the settlement Croatoan. The significance of the name Roanoke is mentioned off-handedly by one of the characters partway through, but that's it. And no it isn't vital to understanding the plot or the book, but it adds such an interesting layer to the whole thing.
And John and Jane are just cool. They seem like people I'd like to hang out with. John especially, he's all sarcastic and snarky and fun. Of course they can both kick some serious butt if necessary.
So... in this one John, Jane, and Zoe have been living as "normal" humans on a colony for a while until they're chosen to be the leaders of a brand spanking new colony. There are of course complications and much political wrangling behind the reasons for the colony which we don't learn about until partway in.
There's a lot going on for Jane personally, and I think it really helped to have read The Sagan Diary before this. She's finally feeling like she has a home and then they're sent elsewhere and she has all kinds of Special Forces stuff shoved back at her even though she's past that. It's such an interesting concept, she's barely a teenager chronologically and yet she's mother and leader and wife. Which is a heck of a lot to deal with if one is emotionally a teenager! And to be dealing with it and then be shoved back into what you used to be... quite the thing.
I also really liked the Stross character. He's so spacey (heh, in more ways than one!) and interesting. Perfectly happy just floating around in space studying literature.