Today I came to realise an important reason for upgrading from Grails 1.1 to 1.1.1, the staging sites running on Tomcat were not allowing updates to data via GORM due to this issue.
My most recent contributions to the project worked fine on my local system, but that was just a stand alone Jetty running courtesy of mvn grails:run-app and not much use to the QA team.
So, I figured that it was worth going back to check whether the suggestions provided on the grails user mailing list for the maven plugin version issue would work.
Updating the plugins on my local system was fairly straight-forward, so I checked my config changes into version control and fired up a build and deploy through the continuous integration / build server.
The build required a little manual intervention to clean out old versions of plugins, which I was easily able to detect having seen the same error messages on my local workstation.
Deploying the built application onto a Tomcat system that is hosting several related web apps involved a couple of areas of uncertainty, but it did take a while to discover what was preventing the application from starting up. It turned out to be due to there being multiple versions of an underlying jar in the WAR because of a an in-direct dependency pulled in by maven at build time.
I contemplated upgrading the other application to use the same version of the jar, but decided to just set up an exclusion in the Grails-based application's pom.xml for the time being. All seems to be playing together nicely now.
QA can move my task cards across to "completed" - hoorah!