I might just be having a brain cramp but if I want to build a diff file for the differences between 2.6.1 and 2.6.2 I think I need to go to:
http://trac.mu.wordpress.org/anydiff?new_path=%2Ftags&old_path=%2Ftags&new_rev=&old_rev=
and put 1465 for the From and 1500 for the To and that should create a unified DIFF (or a Zip of all the files) that have changed.
So is that right? (its been a long day!)