Excluding cases of hyperlexia, I think most cases of extreme early reading are like ours, in that it is an early sign of an extremely capable learner.
This is starting to look like the case for my DD but she is also as asynchronous as a child can be. She isn't one of those super poised youngsters who is wise beyond her years. Manipulative, yes, but wise? Not so much, at least not yet.
One observation I do have about members of SO's family who read early is that most of them either became engineers, musicians, or both. None of them seems to have a life-long love of literature so it'd be interesting to see how DD evolves.
