According to the wiki we still have some open blocks/areas.
http://wiki.apache.org/cocoon/MergingBranches
In addition it seems that some new things have been checked in only to one branch, either trunk or 2.1.x, but not to both. Could everyone please verify that all patches, fixes etc. are applied accordingly? Of course, there are features that should only apply to 2.2.
I see a successful merging as a minimum requirement for the 2.1.6 release.
What else beside merging? I'd say checking out all tests and samples is another required step. Going through TODO/Bugzilla items to identify blockers could be the third thing. I'm aware of at least one open issue [1] which could be addressed in 2.1.6
Vadim
[1] http://marc.theaimsgroup.com/?l=xml-cocoon-dev&m=109596886721684
