scm:validate for svn currently only validates the URL has a good format, but nothing about its actual validity.
The first thing that could be done is to offer a way use the svn info output, retrieve the "URL:" line and check if it matches the project/scm/developerConnection declaration (or one of them?).
This would be useful to the release-plugin. A lot of people already got burned by the svn copy that would actually copy something else that the current project content to the tag because the URL was wrong (see MRELEASE-512 and MRELEASE-494 and
MRELEASE-445 for just some examples).
Currently working on a patch for it. But if you have any feedback, I'd be glad to hear about it.
Cheers and thanks for the work guys.