At the Saturn Awards, Bourne producers Frank Marshall and Pat Crowley discussed the next Bourne film, claiming it may film next summer for a release in 2010. Although the script has not yet been completed, the setting is likely to be South America. The video of the interview is at IESB, and a transcript of some of the comments is at Filmstalker. This is all despite Matt and director Paul Greengrass saying in March they had not committed to another film.
Marshall: Absolutely. Hopefully we will be shooting next summer for release in 2010. There was a fourth book written, but it was not by Mr. Ludlum. So we're probably going to take our own direction and we're working on what that storyline's gonna be right now."
Separately, In Touch magazine has suggested (randomly) that Gwyneth Paltrow may be in the film. Scan thanks to Stacie.