I got my old 2008 macbook repaired from Apple due to a partition map failure in DP3. I got the hard-drive replaced and 10.5.5 as the stock software installed. I upgraded it to Snow Leopard 10.6.0 using my disk. Created an empty partition and installed my Lion GM build off of a USB drive in under 15 minutes. In one line - installed Lion over SL 10.6.0 off of a USB drive in under 15 minutes. Wow!