The Digital Bits has posted their exhaustive review of the SW DVDs coming in a few weeks from Lucasfilm and Fox. Here's a clip of their research:

Simply put, the Star Wars films have never (and I mean EVER) looked this good before. The films presented on these discs absolutely sparkle, in all their anamorphic widescreen glory. The folks at THX and Lowry Digital worked for months to create new high-definition digital masters of these films, transferred directly from the original negatives. Once the films were transferred, painstaking efforts were made to clean the digital masters of dust, dirt, scratches and excessive grain. To give you an idea of just how much work was involved, more than 100 bits of debris were digitally removed from EACH FRAME - ultimately entailing the removal of over 10 million such blemishes in all over the three films combined. As a result, you will not find a single speck ANYWHERE on any of these films. The snow-white slopes of Hoth and the sand-baked dunes of Tatooine have never looked so pure.

Because the transfers were done from the original negatives, you're going to see detail in these films that you've never seen before. You'll notice this right from the opening shot of A New Hope, when the Star Destroyer chases its quarry over the surface of Tatooine. Just look at the subtle swirl of cloud patterns on the planet below - astonishing. Best of all, not a lick of added edge enhancement was required to bring out this detail. What else is good? The color palette here is more lush and accurate than ever before. You're going to be blown away by everything from subtle flesh tones to the vibrant gold plating on C-3PO's chest to the bright orange flightsuits of the Rebel pilots. Contrast is also spectacular, with deep detailed blacks and clear, accurate whites. All three films in this set are just going to absolutely blow you away, and the bigger your screen the better it gets. The Star Wars Trilogy on DVD is the best excuse you're ever going to have to go out and buy yourself a good anamorphic widescreen display. Until true high-definition arrives, it just doesn't get better than this.