Our protagonist, Jenny Casey, is back in the Canadian Army and her firmware is being upgraded with nanites. Earth will be a snowball soon and this particular element of the CA and giant company Unitek are planning ahead: they're making pilots for colony ships out of teenagers, giving them nanites, too. The Chinese have also developed pilots and are also using the FTL technology from the alien ships abandoned on Mars. Conflict on Earth spreads to space and crazy maneuvers are tried to save as much of the Earth as possible, mutiny occuring in the process. The AI helps, but the people make the decisions.
People you like die -- I spent last night stopping to be sad -- but the book has wonderful plot and conflict, characters and relationships. I'm looking forward to starting Worldwired tonight.