A quick update: I'm about 20% of the way through book two of the DARWIN series (still working on an over-arching name for the three books). I'm very excited about how it's shaping up. The outline has been through a few rounds of brainstorming and feedback with my editor at Del Rey, and is so much better for it.
The second book isn't due until mid-august, but I'm shooting to finish the first draft by May 15 so that I have three months to revise. Hopefully I won't need all of it, and can get cracking on book three early. We'll see!