XWiki Enterprise 3.1 Release Candidate 1 was a bug fix and stability version only and as such there are no new features.
Bugs fixed since 3.1 Milestone 2 by going to:
ReleaseNotesXWikiEnterprise31RC1
And download the new version:
Download
XWiki Enterprise 3.1 Release Candidate 1 Available
Version 1.1 by Caleb James DeLisle on 2011/06/07
