Judge Dietz talked about the new courthouse a bit yesterday during the Downtown Austin Plan discussion.
You can find his part on the "Item 2 (Part 2 of 2)" just after the 30 min mark from this link...
http://austintx.swagit.com/play/01192011-110/0/
Some key points he made... The first floor will be commercial and civic use. They are going to Brooklyn to look at their multi-use federal courthouse. They need 500,000 sq feet and that is excluding basic stuff like common areas, and maintenance spaces. He said "We believe this will be a downtown building who's tenet coincidentally is a courthouse." They are looking at making it open to a plaza that opens onto the park, making that plaza as something of an extension of the park. Also mentioned that they have over 300,000 visitors a year so that is a lot of people that will be going there. Much of what he said if feel fairly positive about.