At least Disney says it has. http://www.comingsoon.net/news/movienews.php?id=62442 A statement has been issued confirming shooting has begun in London. The release also confirms the casting even though much of it was already confirmed or rumored earlier. It also has one element I'm sure will drive some nuts-Dejah Thoris is described as a "warrior princess." Start the Xena jokes.
While the news is a relief after all these years and near-misses I can't say that I'm overly enthusaistic. I still have some issues with certain decisions that Andrew Stanton has made concerning this film and whether or not he is even the right person to make it. But at this point there is no turning back. So I wish the cast and crew good luck and have a good production and make the best film you can.