Disney Publishing Worldwide and its Hyperion imprint know a good thing when they see it. And at a press conference held at the Bologna Children’s Bookfair late yesterday afternoon, DP VP and US publisher John Yaged happily told the crowd that the company has signed Rick Riordan, author of the bestselling Percy Jackson and the Olympians series that has sold more than 1.6 million copies Stateside, to create two more original fantasy series.

The details about Riordan’s new fantasy series in the works are under wraps, but Yaged did say the second one, Camp Half-Blood, is being spun off from the Olympian books and will center around the training camp for young descendents of the Greek gods featured in the Percy stories.

Before that happens, however, Riordan will complete the five-book run on Percy. The fourth title The Battle of the Labryinth is on deck to follow-up the New York Times bestseller The Titan’s Curse on May 6, hitting US retail outlets with a substantial one-million-copy hardcover print run. And to stir up interest prior to the release, a new web portal (www.percyjacksonbooks.com) launches this month to house all things Percy-related.

According to Yaged, Fox is working on a theatrical film based on the first Percy novel, The Lightning Thief, for a fall 2009 release. The story revolves around dyslexic, ADHD-afflicted Percy discovering he is, in fact, Greek sea god Poseidon’s son.