As mentioned yesterday, Ubuntu 13.04 will likely ship with the Linux 3.8 kernel -- three releases ahead of the Linux 3.5 kernel currently found in Ubuntu 12.10 and there's been many DRM/KMS driver improvements since that point.
When it comes to the X.Org stack, X.Org Server 1.14 is hoped for assuming there are no major delays with that next xorg-server release. The 1.14 is hoped for release in March with new features. Among the work likely to land is improvements for DRI2 offloading / on-the-fly GPU switching, likely the integration of XWayland, and the possible DRI3.
As far as the DDX drivers go, it will be whatever is the latest version is available at the time they pull the latest code prior to feature freeze.
The latest Mesa release will also be pulled, which should become to be known as either Mesa 9.1 or Mesa 10.0 depending upon how far they get with reaching a major new version of OpenGL compliance. The next milestone to hit will be OpenGL 3.2/3.3 for the open-source graphics drivers while achieving OpenGL 4.0+ is very unrealistic to see for the next six-month Mesa release. Aside from new GL support, there will continue to be much churn throughout all of the Mesa/Gallium3D drivers thanks to the upstream developers.
As mentioned already this morning, Ubuntu developers are also hoping for improved hybrid graphics support in Ubuntu 13.04.
The Ubuntu 13.04 repository should also pull in the latest Wayland release, which will either be Wayland 1.0 or likely some 1.0.x point release. However, not talked about this week at the Copenhagen UDS was using Wayland as an Ubuntu System Compositor -- something originally targeted for Ubuntu 12.10. I still see it as unlikely that Wayland will play any significant role in Ubuntu 13.04. Wayland/Weston will continue to be packaged and likely serve for experimenting with the new display technology and maybe some primitive desktop application support (assuming they build out GTK and Qt5 with the Wayland back-end enabled), but I will be very surprised if they push it into any default installation for the Raring Ringtail.
That's about it for the general X.Org plans for Ubuntu 13.04.