I tried the URL in Firefox and was shown a list of Subversion repositories. Exactly which version of messaging do you want? The latest development version is at http://anonsvn.jboss.org/repos/messaging/trunk, while the various released versions are at http://anonsvn.jboss.org/repos/messaging/tags/. For example, 1.2 beta2 is at http://anonsvn.jboss.org/repos/messaging/tags/JBossMessaging_1_2_0_Beta2/
Really sorry for that, trying with svn or sublipse really does not work, but using firefox, I was able to list as you said, with the full path sublipse was able to fetch the project.
Sorry for the inconvenience
Just found a minor bug on the project, issuing a jira (mbean for queues are set as org.jboss.jms.server.Queue, should be org.jboss.jms.server.QueueService)
1.2 is as yet unoptimised. So don't expect any great performance.
In the next few weeks we will be going through system optimisation, during which time we will get the perf framework up and running again (this hasn't been used since 1.0.x).
If you're willing to give us some help getting it up and running that would be great :)