Look around on imdb or horror websites, such as bloodydisgusting. There are numberous story articles on imdb alone.
Wes Craven is undecided since his last involvement with Dimension/TWC wasn't a pleasent one (Cursed). And no one knows about Neve, as she had a limited pressense in Scream 3.
But it is scheduled for a 2010 release.
There was also an interesting story about how the Weinsteins signed a 80 movie exclusive deal with Showtime, that the next 80 films to come out through the Weinsteins would be preimiered on Showtime first. Included were a RoboCop remake, I believe the Pirahna remake (not sure), and Scream 4.
Edit- Here are some 'exclusive facts' (Bloodydisgusting)
Kevin Williamson is writing a draft for the film, Wes Craven may or may not direct, but is likely to, they are making offers to the Arquettes and Campbell for cameos, and it will be a 'younger version' of the Scream movies.