The report comes from Deadline, who point out that the process had already been well underway. The Phantom Menace was released last February in 3D, and Attack of the Clones and Revenge of the Sith were both scheduled for next fall.
Phantom Menace's 3D conversion was met with a generally lukewarm reception, but our own Eric Goldman screened some footage from Clones and Sith 3D at Star Wars Celebration this summer, which prompted him to say that it seems the two films have "undergone a very impressive 3D conversion that is far superior to the one The Phantom Menace had."
The original plan, revealed in 2010, was to release all six of the live-action Star Wars movies in 3D at the rate of one per year -- back when there were only six live-action Star Wars movies, that is. That appears to be off the table for now, because, you know, we're getting more live-action Star Wars movies!
Update: StarWars.com has offered up an official statement on Deadline's story, saying that "Lucasfilm has decided to postpone this fall's scheduled release of Star Wars Episodes II and III in 3D. Given the recent development that we are moving forward with a new Star Wars trilogy, we will now focus 100 percent of our efforts on Star Wars: Episode VII in order to ensure the best possible experience for our fans. We will post further information about our 3D release plans at a later date."