The major items that Adam is looking at from DMX-2 include support for Composite when using Xinerama, exposing animated cursors to the DDX for acceleration, integrating RandR and Xinerama at the protocol layer, and various performance optimizations for for redirected windows and MIT-SHM.
Adam has re-based all of the old DMX-2 DIX (Device Independent X) code against the latest master code, which can currently be found in this branch. Nothing has yet been merged to the X.Org Server master branch, but there is currently an ongoing discussion.
X Server 1.8 just recently entered its bug-fixing state where no new features are supposed to be committed, but there's always room for exceptions. Otherwise this work will likely end up in X Server 1.9 to be released in late 2010.