The release will most likely be done from the master branch. The only other one is for olap4j 2.
About the maven-release-plugin. We can use the maven-release-plugin for olap4j-xmlaserver. That would be much simpler than my usual manually-deploy-and-test procedure. As for the core olap4j code, I'd rather we wait until olap4j 2 before making changes to the build system (it is currently based on subfloor/ant). The code is not nicely split into proper modules. If we migrate to maven, we should split the core API from the XMLA driver and the experimental packages. Making these changes now seems like overkill, and quite frankly, I don't think anyone has the bandwidth to do it right now.