Diaspora is finally available, to a select group of investors and mailing list actives.
Most of the media attention is focused on Diaspora's concept of aspects, sub-groups within your list of friends who represent different aspects of your life. Just as you don't want your boss joining your poker game, or your wife seeing your mistress, Diaspora thinks aspects deliver the choice, ownership and simplicity Facebook lacks.
The Facebook response has been to deliver a groups feature, which they say does many of the same things. Maybe, maybe not.
The real question is how Diaspora might seek to monetize itself, without creating the privacy trips that some say tripped up Facebook.
Of course many say those trips didn't trip up Facebook at all. The site is still growing. It's now a dominant presence on the Web, bigger (it sometimes says) than Google itself (although they're about completely different things).
The challenge for Diaspora -- for any challenger -- is convincing masses of people to try a second social network. The open argument worked against AOL back in the day, but Facebook is on the real Internet and uses open source tools for its development.
If people can be convinced to join, then Diaspora has to scale its development process. Facebook is organized. It has gone through that process. You're not going to maintain a competitor with just the four partners, no matter how well they code.
So in the end this becomes a business battle. Is Facebook vulnerable as Yahoo was or impregnable as Google is?
Time will tell.
Meanwhile we have the illustration above, from the Diaspora home page. Is it a small group of flies deserting a seal carcass on the beach? Seagulls landing on a rock? The Rapture?
After you've had your turkey come back and play the game of let me know.