Nice pics. That building at 5th & Mopac is Capstar at Compass Plaza. They only have one more floor to go. It'll be 100 feet tall.
While at the Trail of Lights, I noticed a booth that had some amazing photos of Austin. I didn't get a chance to stop and look, but as luck would have it, I found their Flickr page.
Check these out, there's some stunning photos of Austin here.
http://flickr.com/photos/8898332@N07/