Well i got a reply from the person who was at the Blu-Ray preview at the Disney offices and it does look like we are getting the same old crappy transfers done for the 2004 DVD set:

As I was also at the launch of the Original Trilogy DVD box set, and spoke to Lowry Digital, who made the digital masters, it is my belief that the Blu-rays are created from the same masters as the DVDs. However, Lowry Digital originally created either 4k2k or 8k4k masters at the time (my memory is a little vague) not 1080p ones. And I believe it is these that have been used as the basis for the new BD transfers. Certainly, they are considerably better than either the DVD versions or 1080i TV broadcasts.