I've actually just heard about Wordpress MU a moment ago and I'm wondering if there's anything unique or different about theming for Wordpress MU that is different from regular Wordpress.
I ask because someone is inquiring if I can work with that. I've only dealt with single user Wordpress. I'm hoping Wordpress MU isn't like Drupal...
Thanks.
Themes use the same template tags in WPMU as they do in single user WP, but there are some things that you want to look out for. Check out http://codex.wordpress.org/WPMU_Theme_Compatibility for more information.
In a nutshell, no. But! If you want to pull sitewide info, then you need specific plugins.
And also check out the page STDestiny linked to. I know I wrote a post clarifying this over at wpmututorials, but no time to go hunt it down for ya. :)