Opera currently isn't served the Javascript files that add the AJAX Drag and Drop features to a course. However if you bypass the browser detect these features mostly seem to work. The drag and drop blocks seem ok, as does moving around course sections. You can't drag the individual resources/activities in a section though. (Tested in Opera 9.02)

If I get a chance in the next few days I'd like to see if I can get this working and add Opera to the list of supported browsers.