I was looking at some of the logging aspects of last, when I realized that it was not showing any changes since Sunday:
benc ttys000 Sun Jun 26 10:07 still logged in
benc console Sun Jun 26 10:06 still logged in
reboot ~ Sun Jun 26 10:05
shutdown ~ Sun Jun 26 10:05
root console Sun Jun 26 10:01 - shutdown (00:03)
After thinking about it, the only system change seems to have been installing the Security Update:
2011-06-26 10:04:32 -0700: Installed "Security Update 2011-004" (1.0)
(log entry from the Software Updates (control panel) > Installed Update)
