From The Digital Bits:
Yeah, we know this is going to get some people's undies in a bunch again... but we can say with some confidence now that when Lucasfilm and Fox release the Star Wars Trilogy on DVD in September, the films ARE going to include new footage. We've confirmed "unofficially" with three separate sources, each in positions to know, that at least SOME new footage is being added to the films, and that more special effects enhancements, tweaks and fixes are being done. We're also told that Lucasfilm MAY include additional deleted scenes for the trilogy on the bonus disc, separate from the material added into the films themselves (rather like they've done with Episodes I & II). We've been told of at least a few changes that are being made, but we're going to wait to confirm them better before we post anything. Keep in mind that we have no idea how extensive or minor the whole of the additions and changes will be. Hopefully, we'll learn more from Lucasfilm in the near future.