"The problem that this aims to fix is really a UI one, not a security one. If you know the user already uses Google accounts and Meebo, there is no need to over clutter your user interface with login buttons to 40 different social networks."<p>This is only a small part of what XAuth can do. From my understanding, 'extenders' can include anything they want in their XAuth token, including session IDs. If you want to, you can allow 'receivers' to automatically gain access to your users' data, without prompting the user to connect their account to the receiver site.<p>It sounds to me a lot like Facebook's auto-connect stuff that is in the pipeline.