Just a quick note - after installing, I logged into one of my bare bones accounts (virtually no-addins to mess with booting) and was promptly alerted to upgrade Google Desktop - fine, and then the notice for 10.6.1 comes up.
Did that and rebooted. Logged back into my minimal account, and all seems fine.
Logged out and then into my "production" account, I got scared. Things seemed to just SIT for quite a while. But it seemed like the fans were kicking on and off, and I could move the cursor, so...
Well, patience is a virtue. I don't know HOW long it took, but I did just let things sit, and FINALLY, the system booted. And, so far, so good, all appears to be working fine.
Had one alert - 1Password, which I love, offered a beta to use with SL when I tried to launch 1Password. I'm game - it seems to be working fine.