Its official that the 2004 DVDs will not be the original versions. They will also not be the final Ultimate Editions. But there is much talk about them having some additional changes to the 1997 Special Editions. Lucasfilm has put changes in just about all of its previous DVDs.

The Phantom Menace - 3 minutes of new effects footage cut into the movie
Attack of the Clones - added 30 seconds of extra footage to Anakin and Padme dialog.
Indiana Jones Trilogy - 14 production equitment removeal changes
American Graffetti - Digitally enhanced sky

Today we got first word on what changes there will be from Lucasfilm. Heres the text from the digital bits below.

I spoke with Ben Burtt recently. He mentioned the upcoming Star Wars DVDs. It seems that they were able to go back and digitize all of the original tracks and rebuild the show from scratch. For the previous Theatrical Special Editions they were only able to go back and re-mix and edit from the pre-mixes which were sonically limited by the analogue recording and reproduction systems of the time. Since Ben was responsible for archiving all of the sound on A New Hope, all of the sounds were able to be found except for a couple of foley tracks which I'm assuming will be re-done. So it seems that we will be hearing Star Wars in a way we've never heard it before. He did not mention if Empire and Jedi would be receiving the same treatment.

There is a rumor that the Han and Greedo scene will be restored as well but there is no word from Lucasfilm on that change.