Yeah, it's happening. Somewhat unexpectedly, since Sam Raimi jumping ship seemed to sink the project, but Legendary Pictures are now pushing ahead with an adaptation of the venerable RTS (and, more recently, life-destroying online RPG) series.
This news may attract a lot "Meh," from the audience, but there are two interesting things about the announcement. The first is that their director of choice is Duncan Jones, who previously helmed Moon and Source Code. Jones is noted as a more thoughtful, minimalist director than what you'd expect for this kind of project. The Hollywood Reporter is also reporting a budget of over $100 million: impressive, but nothing like the $200 million + you'd normally expect of a film of this magnitude.
At this point there is no word on casting or storyline, although Blizzard are going to be heavily involved. Blizzard lore-master Chris Metzen is consulting and advising on the script, so something faithful to the mythos is to be expected.
At this stage there is no word if an ironically Jack Black-voiced Pandaren will feature as comic relief.