It states that it doesn’t require major changes because it all happens under the SSH protocol. A new program is needed on the client to sign in and you can already run a custom program on the server to authorize the key.
I stand corrected. Still not sure I'd want to expose my SSH infrastructure to the massive kludge tower that is OpenID, but it not being its own implementation of the actual SSH protocol is a huge plus.
I imagine it wouldn't be for the system admins to use, it's for all the other users who can use terminal applications but always treat ssh keys as a nuisance and try to avoid them as much as possible.