Aaron gave me a great suggestion for the WordPress MU update script: pull the latest version directly from the download page. So I’ve added that as an alternative method. If no specific version is passed in, the script will pull down the latest, determine what version it is and check to see if it already exists before continuing with the installation (upgrade-wordpress-mu.sh).

I haven’t actually had the chance to fully run it through its paces yet, so we’ll see for sure when the next update is released.