Lucasfilm knew from experience how anxious people were to get even the most meaningless glimpse of Star Wars in production. It had to deal with a massive number of spoiler-driven fan sites, tabloids, the entertainment press, paparazzi, and even a stolen copy of the AOTC script.
So when ROTS went into production in 2003, Lucasfilm decided to give fans “access” to the set in Australia with not only online chats with various folks involved with the film but with webdocs, photos from the set, and the super popular webcam. Of course to access stuff like the webcam you had to shell out for premium Hyperspace membership but it was unprecedented. By being so open about the film, Lucasfilm could give the fans what they wanted but still remain in control of what comes out. The people determined to find out the entire film in advance were going to do it anyway but for others who just wanted to speculate or get a glimpse of how our heroes look, there was plenty to keep us busy for two years. There were a lot of interesting moments caught at random on the webcam but for me the highlight was when I happened to be folding laundry when the webcam switched over to Ewan McGregor, Hayden Christensen, Nick Gillard, etc. rehearsing the film’s big duel. That was awesome!
Compare that to the near-radio silence on Episode VII. Times have sure changed.