Xibo python client source code is available at bzr branch lp:xibo pyclient.
The client and related libraries, mainly libavg (http://www.libavg.de/) and berkelium (http://berkelium.org/), would have to be modified for the platform in order to take advantage of the SGX Video acceleration to play video and perform several optimization for web page rendering.
The libraries used by Xibo have already been cross-compiled and Xibo python client can run in qemu for beagleboard/overo as shown at http://www.cnx-software.com/2011/11/04/xibo-digital-signage-on-arm-full-version/.
All features seem to work in the emulator (could not test video due to performance issues), but the software needs to be tested on the actual hardware and optimizations are most probably needed to achieve smooth results.
Note: I am not related to the Xibo development team.