The Zohar 4: Pritzker Edition
Stanford University Press started a grand project in 2003 to publish the Zohar in 12 volumes. Daniel Matt is translating the text and writing the extensive commentary. The fourth volume was published last fall. The Stanford Report wrote an article about it last week. Most of the piece are segments of an interview with Matt, on such topics as the difficulty of translating the text and the history of the various translations. In short it gives the context of the work.
The book's page at the pubisher's site