The following screenshot shows, on the left, the Activity menu for Moodle 1.9 and, on the right, the latest version. There is not much to notice at first glance. The Workshop module, disabled in 1.9 is now enabled. What else?
Hot Potatoes: Whereas before the Hotpot (Hot Potatoes) module was available but disabled by default (with its eye closed), in Moodle 2.0 it is now a contributed module and will need to be installed separately into your Moodle. It can be downloaded from http://moodle.org/ | Downloads | Modules and plugins
Feedback: A contributed module in 1.9 this is available in 2.0 but needs to be enabled (have its eye opened) in Site administration | Plugins | Activity modules | Manage activities. Eventually it will be replaced by a brand new module combining the best of both the Feedback and the Questionnaire modules.