There's a meeting at Chiron's Big House with all the head counselors (which now includes Leo and Piper).
They tell everybody about the other demigods in the Roman camp.
Chiron explains that the Romans fought Titans in the Bay Area while the Greeks were fighting them in New York, and that the gods just lied to both sides so they wouldn't find out about each other because whenever they know about each other they try to kill each other.
Annabeth says she's going with Jason to find the Roman camp when the ship is done.
They've figured out that Percy Jackson is in the Roman camp, probably with amnesia. (And if you want to find out about that, you'll have to read the sequel, Son of Neptune.)