Upgrade to PHP 5.2 or above

The Error Message you see is by WordPress. It’s very misleading what it basically saying is, that you need a PHP version >= 5.2 for that feature to work.

Please look into your operating systems documentation or contact technical support on how to update your PHP version. For CentOS, for example: CentOS HowTos: PHP 5.1 To 5.2

Keep Timezones Upgraded

To get the most out of PHP Timezone support, there is a PECL package that contains all the latest updates: timezonedb.

So next to upgrading PHP to a recent version, you can install that PECL package and keep it updated to get the latest timezone updates (last one was on August 16):

$ yum install php-pear php-devel
$ pecl install timezonedb