I was just thinking that maybe a UMD is actually just a slightly smaller dual layer DVD in a shell. Both operate on the same wavelength (660nm) and the storage capacity is actually consistant with dvd. Remember the last time a "proprietary" format was used on the gamecube, it ended up being just a dvd. Could be the same here though an even heavier case mod would be needed. Worth inverstigating I suppose, especcially since the filesystem is standard.