Sam Spilsbury has announced via his blog that the OpenGL ES support was merged into mainline Compiz. "That means as of now, you can build lp:compiz on a platform like the pandaboard below and expect it to run as it does on the desktop...It also means that we’ll be able to deploy compiz on any other platform that implements OpenGL|ES 2.0." This comes after KWin and GNOME Shell / Mutter have already supported OpenGL ES as a subset of OpenGL.
Though with Compiz now only using a subset of OpenGL extensions that work on both desktop and mobile/embedded, there may be regressions and not all Compiz plug-ins are working at the moment. "Of course, in order to port us over to OpenGL|ES, we have to use a subset of OpenGL which is common to both implementations. This meant that a number of plugins have been heavily altered to do this, and some plugins do not work at all at the moment. They are disabled for building and will be ported later if there is enough demand for them to work."
This Compiz work will be found in the forthcoming Ubuntu 12.10 for use in conjunction with the Unity desktop.