Personally, I see more benefits and more convenient to have the release scripts in SVN.
Based on what you explained, Ignasi, I tend to agree - especially to break the "circular dep" between using the release script to generate the release and having to tweak it.
SVN seems fine for me - I'd then just say that we should include those things that are already in the "scripts" directory in jclouds/jclouds there too.
Regards ap