I have 2 sites.
1 - joomla 1.5 + jomsocial - there are my users
2 - bitrix 10.0 - my online store - now is in development
What i want:
When a user tries to log in to bitrix site, he can see a button "Log In with Your Joomla Username".
If this is first time user log in to bitrix site, new user is created and user info grabbed from joomla site.
Bitrix fully support OAuth and OpenID, the main task is to configure joomla as authorization server.