From marketsaw [via darkhorizons], [Cast so far includes] Ian McDiarmid, Harrison Ford, Carrie Fisher, Mark Hamill, Billy Dee Williams, Anthony Daniels, Warwick Davies, Benedict Cumberbatch and Gary Oldman. I believe Cumberbatch and Oldman were pursued for the same role, but I don't know how that will work out with the script changes, but I'm told they are both involved.
Regarding Harrison Ford, two more Indiana Jones features are in the negotiation stages as per Ford's contract clause on Star Wars, which is the primary reason he didn't 'publicly' or 'privately' commit, or so I'm told.
Many Star Wars pre-production issues, an 'inadequate' central story which nobody would stamp off on, a problematic initial release date and an 'indecisive' director (J.J. Abrams) with the hardest gig in the industry. It's not going to be a cakewalk, but it will be a product shipping with the majority of its original parts.
Ultimately it's about twins, and which will take a path towards darkness and which will follow in their fathers footsteps, or at least that is what it used to be, that may come later as I think changes are being undertaken to bring the original cast into the forefront of the story leading to ramifications that lead up to the next generation of Skywalkers."