The site was relaunched running on Pantheon today! A big thank you to Pantheon for hosting the site as part of their "Give Back" program that provides free hosting to Drupal sites that support the community. This is the second site I have launched on Pantheon. The first was a new site built from day one with Pantheon in mind, the experience was great. This site was imported from a previous build, running multi-site under Aegir. There were a couple bumps, but it still was a great experience.
There is a lot about Drupal that is pretty awesome, upgrades and content migration don't top the list however. Trevor James's new book, Migrating to Drupal 7, is published by Packt and takes a look at a couple ways of getting existing content into Drupal. The two most common ways are the Feeds module and the Migrate module, both are touched on. Additionally the Drupal 6 to Drupal 7 upgrade preocess is covered, as well as importing content into Drupal from Wordpress.