OpenID is an increasingly popular way for providing single sign-on and federated identities for users of web services.
MidCOM has supported OpenID registration and login for a while now (http://bergie.iki.fi/blog/midgard_supports_openid/), and while that implementation should be checked for functioning, we also need an implementation that goes the other way: allowing users utilize their Midgard accounts for login and registration to external web services.
The OpenID identity URL should probably be the user's n.n.accounts profile page (see for example http://maemo.org/profile/view/bergie/)