X.Org Server 1.15 is now under a feature-freeze but just before that happened, DRI3 support including the new Present Extension, was merged.
For the past year Keith Packard at Intel has been spearheading the new DRI3 extension
for the X.Org Server. DRI3 (a.k.a. DRI3000) was originally conceived at XDC2012 in Germany while now it's ready for xorg-server 1.15. See this article
and the many others
if you aren't yet familiar with this major advancement to the Direct Rendering Infrastructure.
Beyond merging DRI3 changes to xorg-server master, Keith also put out dri3proto 1.0
and presentproto 1.0
More details on X.Org Server 1.15 will come in another Phoronix posting shortly.