ACR opensource Turbogears2 CMS got support for user permissions to allow users to edit only some pages and create children only in some sections. This should permit to separate work between multiple people in ACR based sites.
ACR also got support for blog/news slice template. This permits to create blogs in ACR with just two clicks instead of having to declare the ACR slicegroup youself.
As usual you can download ACR from http://repo.axant.it/hg/acr by using mercurial