Yes , they are making a movie adaption of the books. I met Lauren Kate when she was in Australia and she sinabi that the rights to the films were bought sa pamamagitan ng Disney and that the script for the film has just been finished. No one has been officially cast, however there have been several rumours (thanks to IMDb). Also, the film is set to be released in 2012 and will be directed sa pamamagitan ng Saul Cajacuri.
I'll give you the link to the IMDb page, however any of the cast that is listed on the page is not official as yet, so they will probably change.
Anyway, here's the link:
link Sorry if my answer was too long. I hope it helped.