If you're extra-drowsy this morning in the USA, you're not alone. The switch to Daylight Saving Time over the weekend, moved earlier last year, leaves us scratching our heads in sleepiness for a few days... although, according to a recently-published study, the DST-associated rise in automobile accidents may be mythical (still, please drive carefully!).
The good news for anyone on Mac OS X version 10.3.9 or higher is that the 2007 DST changes are reflected automatically in software and should not require any special handling. There are a couple of things to keep in mind, though... first, if you use Entourage 2004 or 2008 and it's been running through the weekend, you'll need to quit it and relaunch before it recognizes the time change.
Second, remember that while your machine is patched and fully DST-aware, your colleagues or collaborators (particularly those overseas) may not have the US daylight rules completely sorted out. To avoid scheduling mixups, if you are planning events between 3/11/08 and 4/1/08, you may want to include the exact time and timezone of your meeting in email subjects or event names.