Need a twitter plugin that will show tweets from all site users automatically

Hi,
I am looking for a plugin like tweetblender that will take the Twitter usernames that our WP site users have entered in their extended user information page and merge them together in a widget.

As far as I can see tweetblender does this, but not automatically – ie – if a new user joins the site I want their twitter to automatically join the list of tweets in the widget.

Does anyone know if this exists?

If no, would it be difficult to hack tweetblender to do this?

Thanks,
Jonathan
The Flaneur art blog