Is there any probability of XBMC supporting the VIA VX900 Media System Processor (
link). With the release of VIA VE-900 motherboard with VIA Nano X2 processor (
link) seems to be a nice solution for a cheap htpc.
On a side note the VX900 seems to be in the same position as Broadcoms CrystalHD which is supported in XBMC.