John,
The auto-mapping isn't something we've implemented yet for JLinked v2.0. We're in the process of updating it (and JFBConnect) to support Joomla 3.0. While some features for JLinked v2.0 have been added, that's not one yet. However, I looked at the code to do that in JFBConnect (in the /components/com_jfbconnect/controller.php file around line 51). It's only about 20 lines of code, and shouldn't be too difficult to update the same functionality for JLinked. I'll try to look into it sooner rather than later to let you know what we find, but if you start and have any questions, just let me know.
As for more social integrations, yeah, that's definitely on the plate. The updates to JFBConnect and JLinked were supposed to be out by this time, but one of the things that slowed things down was a slight change in plans to unify our profile plugins. We're now updating the profile plugins into a new group of "social plugins", instead of jfbcprofiles and jlinkedprofiles, that can be used for both extensions. That will also greatly help with adding more social login functionality down the road, with Twitter being a high priority one for us over the next few months.
Hope that helps, but let me know if you have any questions, feedback, or other thoughts.
Thanks,
Alex