Publishers Weekly just posted the news:
Jill Santopolo, executive editor of Penguin Young Readers' Philomel imprint, took world rights to a new YA novel by David Levithan and Andrea Cremer called The Invisibility Curse. Bill Clegg, at William Morris Endeavor, brokered the deal for Levithan, who co-wrote Nick and Norah's Infinite Playlist (and is editorial director at Scholastic Press). Richard Pine and Charlie Olsen, from Inkwell Management, represented Cremer, author of Nightshade (and history professor at Macalaster College). The novel follows a boy burdened by invisibility who meets a girl that has the power to see him and, possibly, cure him. Publication is currently set for 2013.
I'm reading Nightshade and it's going great, and I've heard awesome things about David's work (I've got Leviathan and Behemoth ebooks to read!). Adding The Invisibility Curse to my TBR list right now!