ssh_proxycommand should use msva
msva now has the capability to verify openssh keys (pkctype: opensshpubkey). The ssh ProxyCommand function can pull the key from the host with ssh-keyscan
In fact, a working prototype is in 7244f4400ed9eb1527ef18854b65608d31a092b4. If the MONKEYSPHERE_VALIDATION_AGENT_SOCKET variable is set, then the msva query function will be used. If not, then the regular old monkeysphere method will be used.
(from redmine: created on 2010-10-30)