So on July 28, 2010, Sue Rostoni, executive editor and fiction & comic editor at Lucas Licensing, confirmed that a novel based on the Master of Darth Sidious (the Emperor, Palpatine) was in the works for a release date in just under two years (February 28, 2012).
It's a little while away, but I'll be waiting with great anticipation! When Sidious told Anakin the 'Tragedy of Darth Plagueis the Wise' I was extremely interested, and now we'll get to read it. It will be written by James Luceno who's written quite a few SW novels already, although I have never personally read any of his work.
The book was originally due for release in October 2008 but it was removed from the publishing schedule and replaced with Darth Bane: Rule of Two (which is an excellent book - you should really read the Darth Bane series if you get the chance) because of continuity issues and confusion with Palpatine's backstory.
I'm looking forward to this - you?