So far I've tested it against 2.6.25.17 and 2.6.28 on both x86 and x86_64 with reads, writes, directory creation, symlink creation, and mmap() and it seems to work fine.
Just give it a range of memory on the bus, or the domain:bus:device:function numbers of a VGA PCI device, and it will mount the VGA video RAM and allow files to exist there.
As a special hack: you can also specify the size of the active framebuffer console so that fbcon doesn't collide with this driver (unless you want to see what your files look like splattered across your screen, ha). The active VRAM area becomes a "sentinel" file named "framebuffer".
What do you guys think?