Attendees included: Ismail Mayat, Warren Buckley, Jesper Ordrup, Hendy Racher and Harald Ulriksen.
Hendy was the only person attending who had done a custom memberhsip provider, and recommended inheriting from the Umbraco provider and overiding neccesary methods.
The talk quikly turned to other means of authentication based on IP addresses, Open ID, RPX and SAP
IP authentication only is not recommended, but "required" by some customers. This can be solved using custom controls and programatically login the user.
Jesper has a working prototype for RPX available which works for both users and members and will try to create a package at some time. Harald will release his OpenId Member package after code garden, however it will not be made as a membership provider but as user controls. See projects for more info.
For solutions including SAP it is common to export user data (with hashed passwords) to a separate database and then authenticate the users against the database instead of SAP.