XWiki Enterprise 4.0 Milestone 2 is the second ans last milestone of 4.0. This version mainly introduces various ways of customizing users directory and profiles and it also bring all comments features to annotation (answer, threaded annotation, etc.) by merging the two concepts in one comment with optional precise location.
See http://www.xwiki.org/xwiki/bin/ReleaseNotes/ReleaseNotesXWikiEnterprise40M2 for more details.
See http://jira.xwiki.org/secure/IssueNavigator.jspa?reset=true&jqlQuery=category+in+%28%22Top+Level+Projects%22%29+and+fixVersion+in+%28%22%34.%30-milestone-%32%22%29+and+resolution+in+%28%22Fixed%22%29 for more details