Lucasfilm President Kathleen Kennedy has formally announced the formation of the Star Wars Story Group "to oversee and coordinate all Star Wars creative development including licensed books, comics, and games."  This group (originally leaked in January, see “One ‘Star Wars’ Canon”) decides what is "canon" and what is not, and will make sure that future licensed Star Wars narratives fit within a general continuity.  At this point the Star Wars "canon" includes the six original Star Wars movies, the Star Wars: The Clone Wars animated series, the upcoming Star Wars: Rebels cartoon series, and a new series of novels to be published by Del Rey that will be the first ever canonical licensed Star Wars books.
Reprints of EU Titles Will Carry the "Legends" Logo
In a statement on the Star Wars Website, Lucasfilm deals explicitly with the vast amount of narratives that have been added (via the hundreds and hundreds of licensed Star Wars novels, games, and comic books) to the six original Star Wars movies, which basically only cover the lifespan of Annakin Skywalker.  This so-called expanded Star Wars universe, which both precedes and follows the events of the movies by hundreds of years, will not be consider "canon," though contemporary creators like the producers of Star Wars: Rebels can use any of the elements from the Expanded Universe that they want, and new printings of the pre-2014 Star Wars Expanded Universe books, comics, and gains will carry a "Star Wars Legends" logo to indicate that they are not canon.
Dismissing the Expanded Universe as non-canonical allows the filmmakers of Episode VII, which takes place after Return of the Jedi from having to tell the same story as the post-Return of the Jedi Expanded Universe tales.  J.J. Abrams and the writers of Star Wars: Episode VII are not bound by anything from the EU, but elements of the EU including The Inquisitor, the Imperial Security Bureau, and Sienar Fleet Systems have been adopted by the producers and writers of Star Wars: Rebels (see "New 'Star Wars' Movies Will Stick to the Canon").
The new movies won’t be the only Star Wars items that will stick to the canon.  Disney and Del Rey have announced four new Star Wars prose novels, which for the first time in the long history of Del Rey’s Star Wars novels, will be considered "canon."  Del Rey VP Scott Shannon told The Hollywood Reporter that he was "excited to finally be able to call our upcoming novels true canon--a single, cohesive Star Wars storyline."
The first of the new Del Rey novels is Star Wars: A New Dawn, which John Jackson Miller is writing with input from Star Wars: Rebels producers Simon Kinberg, Dave Filoni, and Greg Weisman.  It will be released on September 2nd, followed by Star Wars: Tarkin by James Luceno in November, Star Wars: Heir to the Jedi by Kevin Hearne in January of 2015, and Paul Kemp’s Star Wars: Lords of the Sith in March of next year.