Basically they moved Super Admin menus and related pages out of the regular admin and into a new Network Admin screen.
and the updates are:
- Add contextual help for Network
screens - Add delete support to network themes
- Add plugin update notifications,
plugin install, plugin update to the
network admin screen - Admin Bar similar to that used in wordpress.com blogs (#14772)
- Move network version of Tools->Network to the network admin
- Move theme installer to the network admin for multisite installs
- Network Admin (#14435)
- Network Wide Settings->Language Settings
- New Network Admins page for Theme enable/disable/upgrade
- Pass more information to notification filters
- Rename Update menu to Updates in network admin
- Revamp User-new.php including separate caps for adding users vs. creating users, allowing supes to add via email or username, split adding existing users and creating new users into separate forms
- Support wildcard domains in WP_PROXY_BYPASS_HOSTS and WP_ACCESSIBLE_HOSTS
- Tabbed interface for site editing
- User Admin feature creates a separate “personal” dashboard to provide a single endpoint for accessing profile information, cross-site preferences, a launching point for accessing all of a user’s blogs, collation of stats across all of a user’s blogs, a place for a multisite aware quick press, etc. (#14696)