I was working on an install today and my SL boot was always hanging with the "Mac OS Version: Not Yet Specified" printout, which I thought I was told was due to bad extension caches, but I think I ruled that out. I was using the Chameleon RC2 all along, hoping it wasn't really that, but I think I'll have to try downgrading to RC1 now (or in a while, I broke my install by using a different SL Chameleon Support package on RC2, so I need to get home and make a boot USB from my Mac). Hopefully that solves it.