Quote from worthplaying.com (http://www.worthplaying.com/article.php?sid=25594):

“Another day of E3 has ended and today we walked away with an inside scoop. During an E3 presentation, our ever-attentive ears caught the most interesting piece of information. During the Painkiller Xbox demo it was revealed to us that People Can Fly is already working on a sequel to Painkiller — not an expansion pack, like Battle Out Of Hell, but a full-blown follow-up title. No further information or tentative release date were mentioned.”