After years of work and anticipation, Graham Nelson's new interactive fiction development system, Inform 7, is out. The new system is in many ways more different from Inform 6 than OS 10 was from System 9: Code looks like natural language (like English prose, specifically), a new and well-crafted IDE from Andrew Hunter is provided, and numerous improvements to the language and world model have been incorporated. Games still compile to z-code, however, to run on the standard interpreters that run earlier Inform games.
Stephen Granade also offers an overview of Inform 7 on Brass Lantern.