If anyone notices intermittent problems on any of their sites on MT where pages seem to disappear or produce error messages such as:
Fatal error: Cannot use object of type WP_Object_Cache as array in /nfs/c06/h04/mnt/91421/domains/irecusa.org/html/wp-includes/cache.php on line 352
The problem seems to lie with the version of PHP + the WordPress 3.0.1 codebase. You can choose which PHP version to use by adding a line to your .htaccess file such as:
Action php5-script /gs-bin/php5-latest
This will update PHP to the very latest – 5.3.2
More about this here: http://wiki.mediatemple.net/w/Choosing_your_PHP_version_on_the_Grid
Along with this, you may get a PHP E_WARNING message when using the date() function about the timezone not being set. This can be fixed by setting the timezone environment variable:
date_default_timezone_set('America/New_York');