This is the coolest thing since sliced bread. It is a set of OpenSocial Widgets that you can add to your site that makes your site “instantly social”. Take a look:
http://www.google.com/friendconnect/
I want this SOOOO badly. Because I am writing all these widgets as we speak. And my stuff is not OpenSocial enabled – and the Google UI’s are much better than mine – makes me sad to be wasting time – but until I have access to these awsome widgets – I simply cannot wait and have to keep coding. Grrr. Sakai 3.0 needs these as part of ts initial release.
There is a great video:

And a cool sample site:
http://www.myfirstearthquake.com/index_fc.php
I have sent a note to Google pleading for early access.