This seems to be A Thing at the moment. Anyway, Raymond E. Feist is concluding his RIFTWAR mega-saga this year 35 years after starting to write MAGICIAN. The final novel, MAGICIAN'S END, comes out in May. It's fair to say that an awful lot of people no longer care. However, what is a lot more interesting is that we are finally getting the long-gestating RIFTWAR companion volume.

MIDKEMIA: THE CHRONICLES OF PUG is a 192-page, large-format guidebook to the series, featuring tons of maps and background info on the series. Feist is co-writing it with Stephen Abrams, the original co-creator of Midkemia who granted Feist permission to use it for his novels. The book is due on 5 November:

http://thewertzone.blogspot.co.uk/2013/03/riftwar-companion-volume-to-be.html

Meanwhile, a similar book called THE WORLD OF ICE AND FIRE is due for publication on 29 October. This is a 288-page book which is somewhat similar, but is both longer and (from the previews) has a lot better artwork. The book contains new information on the world and backstory. Martin has provided extensive notes on matters such as the Blackfyre Rebellions, the Faith Militant Uprising and the deep mythology of the setting. The book itself was written by Elio Garcia and Linda Antonsson, the creators/admins of Westeros.org and the people GRRM himself consults when trying to dig up bits of info he dropped into books years earlier.

http://thewertzone.blogspot.co.uk/2013/03/more-details-on-world-of-ice-and-fire.html

Both links also link to previews of pages from both books. They're basically the WoT Big White Book, but with proper artwork.