Recently upgraded my system to Mac OS X 10.6, which installs PHP 5.3.0. It also happened to remove my php.ini file, which reset my customizations to error logging, and I noticed lots of error messages like the following:
Warning: strtotime(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EDT/-4.0/DST' instead in /Users/scott/Sites/usic.net/wp-includes/functions.php on line 35
Yes, I can update my php.ini to include the date.timezone setting, but I strongly recommend that a call to date_default_timezone_set() be instrumented somewhere in WordPress. Given that the system asks me what time zone it's in, I'm a little surprised not to see the system then set the default time zone anywhere.