The register event in dnn does not really bubble up to any point where you can easily hook into.

But having said this - I guess a lot depends on how you you handling your authentication for a new user = are you creating a dnn user account automatically ?

If so then you should be able to access the userid yourself during this process ... we did something similar with our facebook provider - but went further - to incorporating options to association fb accounts with existing users as well - and to also letting the user select their own username and password for the dnn account site.

Since we are controlling all the rego and login from inside the one module we have full access to the userid inside the module - we also created a custom rego module for one particular site as well that allowed the user to handle facebook login / rego from both the login and registration pages - oh and its all fully popup compliant with dnn600 - www.loyaltepays.com has a demo of this module.

Westa