Ricardo Salveti, the platform development lead at Linaro, tweeted, "OpenGL ES 2.0 support is now upstream for Nux and Unity. Once Compiz porting is done, Unity 3D will work with GL ES by default on Ubuntu :-)"
The OpenGL ES 2.0 work is part of this Launchpad Blueprint. For a while now the Linaro and Ubuntu developers have been after upstream OpenGL ES 2.0 support for their Unity (non-2D) desktop, and it looks like the goal will be realized in time for the Ubuntu 12.04 "Precise Pangolin" LTS release in April and the Linaro releases shortly thereafter.
Having OpenGL ES 2.0 support will allow the Unity 3D desktop to work on more mobile devices where only OpenGL ES is exposed and not the full-blown OpenGL specification. This support will also be important for some set-top boxes and TVs, among other embedded areas where Canonical/Ubuntu has future ambitions. OpenGL ES is also exposed by Mesa/Gallium3D so even on the desktop the OpenGL ES paths could be used as well. If GLES support is advertised, it will be used by default in Ubuntu. Unity 2D will continue to be around for those without 3D/OpenGL acceleration.
The Compiz window manager is the last piece of the puzzle that must be made compliant with OpenGL ES 2.0. The Unity plug-in itself now has the upstream GLES2.0 code as well as Nux, which is the OpenGL widget tool-kit library that's used by Unity.
For reference, KDE has had EGL/OpenGL ES 2.0 support within the KWin since the KDE 4.7 release. The Clutter tool-kit, which is used by GNOME's Mutter window manager among many other projects, also has long had OpenGL ES 2.0 support.