This is something I would be interested in as well. If we could get to a common plugin (Facebook would be good) for Nabble, I could likely do that for my overall site as well and reduce the number of different passwords my users have to use.
Ya Pedro. Most of times users try to login using Nabble id to comment on blog posts.
It would be awesome if you have something on the similar lines.
Currently I have facebook,twitter,wordpress and intense debate logins.