Worst case, I reload a TM backup, or copy over my home directory sans the TM ACLs and go back to what I am doing.I do hope Apple makes a USB flash drive with the Lion install image on it eventually.One thing I will say about OS X: Of all the operating systems I have used except some Linux distros [1], OS X is one of the few that can do a major version upgrade [2] without leaving too much cruft behind