Nikki Finke of Deadline Hollywood broke the story and Nolan is not only prepping Batman 3, but will also be a mentor for the upcoming Superman reboot.
David Goyer and Jonathan Nolan (writers of Begins & TDK) will be returning as well to write the third and presumably last film for the Nolan trilogy.
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The word is that the third film will be focused solely on Batman/Bruce.
Superman's ability to rise to any challenge is always anticlimactic.