Originally, the scope of SSO was defined by the people working on it as excluding Talk; as it was too hard. However, the task for SSO must now include the challenges of tmo/garage account merging and single-sign on.

Given the thought which has been spent on thinking about the general SSO solution, this should be straightfoward (although will require the collaboration of Daniel/Alexey and Reggie).

The process doesn't have to be entirely automatic either. As Reggie, Dave and I did for the council election before last, you can match up a lot of accounts automatically. Where there's many-to-one or one-to-many, these can result in emails to the affected users, a web-interface allowing them to choose one before a certain time and archiving any old accounts which can't be migrated.