PHP Date Errors?

OS X 10.6.2, MySQL 5.1, PHP 5.3.0

I get warnings like:

Warning: strtotime() [function.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/Los_Angeles’ for ‘PST/-8.0/no DST’ instead in /jtsm/wp-includes/functions.php on line 35

I tried setting it in php.ini in the root of my wwwroot.

How does one fix this?