I am thrilled.
After trying all kinds of methods, from manual updates, to svn:externals to handle smooth upgrades in an environment with dev/stage/prod server managed via SVN, this plugin provides an elegant, natural solution.
One nit-pick - it doesn't alert SVN when a plugin is deleted. But then again, it never claimed it would do so :-) This is a minor issue in any case - SVN declares the resource as "missing" and easily deleted during next commit.
Love it - thanks ever so much - will make a donation as soon as I get paid for the first job that uses this little beauty.
Honestly, I would have been impressed if all it did was maintain .svn folders - but the plugin additionally gets the additions and deletions set up in svn? Bonus!