My ideal world solution is that OpenID gets another round of work done so that it can effectively be merged with Oauth and FB Connect to make a simple cross site sign on that allows easy interoperability, it was certainly part of the plan last time I was paying attention. At that point we'd need to be able to support whatever the agreed protocol was and make it easy for our users to refer to Twitter, Facebook and other off site IDs easily.

In the meantime, enabling this as a quick fix would be a workable plan and certainly make it a lot easier for those of us that have cross site discussions and mostly with people using "real" names and Facebook IDs.