What are the services we need to come to consensus on to have a full "Glue SDK"?

First off what are the categories? Second what are the options in each category?

What else is needed to be able to have federated and interoperable versions of each of these?

Authentication

• OpenID
  • Facebook Connect
• Information Cards

   

Identity

• OpenID
• Information Cards

Relationships ("Friends")

• Facebook Connect

Messaging

• XMPP

Data Formats

• RDF
• Atom