railsenvy podcast mentioned this, and that mysql support would be coming 'soon', but since this is ruby 1.9 only, it's not a terribly useful thing until there exists a rails version that fully supports 1.9.
It's supposed to be 1.8.6 compatible but neverblock isn't, I don't think - so I'm not sure what the advantage of this alone would be. I'd like to know, though.
ruby 1.9 has not been released (it is still a dev release at this point.)