I follow the instructions in http://support.apple.com/kb/ht1455 to boot in Safe Mode, but it appears something different happens with Lion. After holding the shift key when hearing the startup tone, the icons for the two accounts I have configured come up as usual. If I hold the shift key after logging in, the screen stays grey and a status bar appears with a "sunburst" waiting animation. (I don't know what the canonical name for that is.) After the status bar fills, the waiting animation continues and then my MBA reboots.
How do I boot my MacBook Air (running Mac OS X 10.7.1) in Safe Mode?