FYI we're serialising the WPMU Manual over at WPMU.org (i.e. completely for free, which is why I figured it'd be OK to share it here :)
The first two articles we've got up are on choosing a host and a domain and setting up your MySQL database and user - really simple stuff to get people going.
Coming up we're gonna be covering themes, plugins, languages, seo etc. etc. etc.
To stay in the loop just grab the feed: http://wpmu.org/feed/
And we'd totally welcome any feedback and requests for topics you'd like to see us cover - just let us know here (or there:) if that's the case.