Canonicity in the Star Wars universe is, as of April 2014 determined by a working group comprised of representatives of Disney and LucasFilm known as the Lucasfilm Story Group.
The primary change made is that the old canon system (G-Canon, T-Canon, etc) has been nuked from orbit and only the original six feature films (the Original Trilogy and the Prequel trilogy, as seen in the 2011 Bluray Edition), Clone Wars TV show, Clone Wars film and Star Wars : Rebels TV shows are considered to be part of the official Star Wars canon.
All other properties (with a few small exceptions) are now lumped together under a single banner known as Star Wars : Legends. Those exceptions seem to include the film novelisations (where they elaborate on things seen on screen), the Star Wars Databank (which replaces the old Databank/Encyclopedia website) and elements of the Jedi Path Manual.
"While Lucasfilm always strived to keep the stories created for the EU consistent with our film and television content as well as internally consistent, Lucas always made it clear that he was not beholden to the EU. He set the films he created as the canon. This includes the six Star Wars episodes, and the many hours of content he developed and produced in Star Wars: The Clone Wars. These stories are the immovable objects of Star Wars history, the characters and events to which all other tales must align."
By definition, the other properties that were originally deemed to be "G-Canon" and "T-Canon" (the Star Wars Radio Dramatisations, Star Wars Holiday Special, Ewoks films, Star Wars : DroidsTV show and Star Wars: Ewoks TV show), along with any deleted scenes, making-of documentaries, behind-the-scenes documentaries, concept art books and previous versions of the scripts are now all considered to be "Legends" properties. Fan-made properties and parodical works (such as the Star Wars Lego series and Family Guy specials) remain completely outside the canon framework
Moving forward, all future properties (films, books, comics and games) will be licensed and fully compliant with the Star Wars Story Groups rules regarding canon status, unless explicitly stated. This obviously excludes future prints of old titles which will be clearly tagged with the "Legends" banner.
Excluding the exceptions listed above, the full list of canon works (past, present and near future) now stands as follows.
(Film) Episode I: The Phantom Menace (and the novelisation by Terry Brooks)
(Film) Episode II: Attack of the Clones (and the novelisation by R. A. Salvatore)
(Film) The Clone Wars (and the novelisation by Karen Traviss)
(TV Show) The Clone Wars: Season 1-5
(TV Show) The Clone Wars: The Lost Missions
(Comic) Darth Maul: Son of Dathomir by Jeremy Barlow
(Novel) Dark Disciple by Christie Golden (not yet released)
(Comic) Kanan: The Last Padawan by Greg Weisman (not yet released)
(Film) Episode III: Revenge of the Sith (and the novelisation by Matthew W. Stover)
(Novel) Lords of the Sith by Paul S. Kemp (not yet released)
(Novel) Tarkin by James Luceno
(Novel) A New Dawn by John Jackson Miller
(Novel) Servants of the Empire: Edge of the Galaxy by Jason C. Fry
(Novel) Ezra's Gamble by Ryder Windham
(TV Show) Star Wars Rebels: Spark of Rebellion
(TV Show) Star Wars Rebels: Season 1
(Film) Star Wars: Rogue Squadron
(Film) Episode IV: A New Hope (and the novelisation by Alan Dean Foster)
(Comic) Star Wars by Jason Aaron
(Comic) Star Wars: Darth Vader by Kieron Gillen
(Comic) Star Wars: Princess Leia by Mark Waid
(Short Story) One Thousand Levels Down Alexander Freed
(Novel) Heir to the Jedi by Kevin Hearne
(Film) Episode V: The Empire Strikes Back (and the novelisation by Donald F. Glut)
(Film) Episode VI: Return of the Jedi (and the novelisation by James Kahn)
(Short Story) Blade Squadron by David J. Williams
(Film) Episode VII: The Force Awakens (and the novelisation by Alan Dean Foster). (not yet released)