First impression, the wordpress network (wpmu) for sites implementation still needs a lot of work. You have to enable it, by adding 1 define to the wp-config.php. Could've just added this to Settings.
If the wp-config.php is writable they should try to make the changes for you, same with .htaccess. It works for subfolders or subdomains, but domain mapping is missing. It can be accomplished in a sloppy way with a plugin so I suppose it's not a big deal.
Custom post types and taxonomies enhancements look great and should make for some interesting new themes.
http://wordpress.org/extend/plugins/...-post-type-ui/