Just talked to kpiwko: shrinkwrap resolver 2.1.0 is out and that's the only version that supports maven 3.1 too. So we probably want to upgrade to shrinkwrap resolver even further (to 2.1.0), in a future PR.
  http://arquillian.org/blog/2014/03/24/resolver-2-1-0/

shrinkwrap descriptors is independent of shrinkwrap's resolver version, but having an alpha version there isn't too good either.