A film adaptation of Rick Riordan's Percy Jackson & the Olympians: The Sea of Monsters was announced earlier this year, set for release 16 August 2013. Most of the cast of Percy Jackson & the Olympians: The Lightning Thief return to reprise their roles, with the exception of Nathan Fillion (who replaced Dylan Neal as Hermes) and Anthony Head (who replaced Pierce Brosnan as Chiron); otherwise, the cast is in tact.
In The Sea of Monsters, Thalia's tree has been poisoned, weakening the protection between the outside world and Camp Half-Blood. The heroes from Camp Half-Blood, lead by Percy Jackson and Annabeth Chase, must travel to the Sea of Monsters—the Bermuda Triangle—to save Grover and retrieve the Golden Fleece, which will restore Thalia's tree.
Personally, I can't wait. The Lightning Thief wasn't a very good movie, but I think they can learn from their mistakes and continue the series strong going forward. The only downside is half the actors will be way too old to reprise their roles in The Heroes of Olympus (the sequel series) assuming they make it that far. Heh.