When I first heard about this, I had the same reaction as most. Of course, that's what we need- another social network.
But actually we do. I haven't been too active yet, but I'm getting into it now.
It's definitely still in its infancy, similar to FastCompany many users are unsure of the structure - how & where to post. The sheer volume of people registering and posting in such a short period of time would appear to bode well. There are some great posts and starting points on Rapid eLearning, instructional design models and even Learning ROI. From a social networking standpoint I haven't friended anyone - yet. Since the conversations are open to all so I'm not seeing the value in that, but the connections will come in time.
I'm still working my Social Media & KM project so I will start seeding questions on Learning Town and see how it goes as well.
In the meantime, I'd invite you to join the conversation and look me up.