According to PTAnderson.com, the auteur has decided on his next film project. It will be an adaptation of Upton Sinclair's novel "Oil!". It marks the first movie that Anderson has made that is not from his own original material.
The site goes on to say that it looks like Daniel Day-Lewis is going to star in the film and that it's a story "of scandal, intrigue and politics." Anderson is currently trying to interest various studios.
Sinclair was a well known novelist and political activist who is also known for the book "The Jungle", which dealt with the meat packing industry.