Of course, this argument is nullified by IIS7’s use of Web App Gallery, which I had managed to test on Server 2008. My understanding is that WPI easily installs most of the common web application packages available today, including WordPress, Drupal and Joomla.
I am curious to learn which setup will ultimately lead to the best CMS. There are many arguments currently out on the web extolling the virtues of Drupal, WordPress and Joomla; but it takes time to experience each of them.