As stated in maven-dev, I think both 2.3.1 and 2.4 are pretty stable now.
The plugins and surefire booter should be up to date for 2.4, and everything should be up to date for 2.3.1, in the snapshot repo. I also changed the parent pom in 2.4 as it used ${project.version}, which doesn't work well with different timestamps on snapshots. I could just deploy the whole tree each time but this is safer. We still need some integration tests to test all possible combinations of forkMode and useSystemClassLoader (and possibly others). So if there are still any regressions or other problems, please let me know. Cheers, Kenney