I now have Beta 2 R2 working on my custom built MSI Big Bang w/ Intel Core i7 950 and AMD Radeon 6770.
Initially I had many issues with networking (since it uses the Realtek 8111 chipset), but setting the swiotlb=8192 boot parameter for netvm fixed all of that.
Previous releases of Qubes either failed to install (the installer didn't load, or the system never booted following installation) - the upgrade to Fedora 18 seems to have fixed everything.
The new installer frontend lacks functionality to setup LUKS + RAID + LVM, but I was able to write a kickstart file and install the system using that configuration.