I'm not entirely sure how newsworthy this is, other than the fact that Amazon has been working with this very quietly, but they have produced a Kindle based social network: Amazon Kindle: Home I discovered it via a posting on Google+ (which is interesting in its own right since I normally find this stuff via Twitter) and went and had a look. This is what you can see:
... which is to say, not a great deal. You can share the books that you've read, and the service will tweet/Facebook status update for you, you can share your notes in books, and you can also follow people. Annnnnnd - that's about it. To be honest, it's difficult to describe it as a social network since the interaction is very limited, it's difficult to see who has read things, as we're limited to initial letters, and it's necessary to expand that to see who is who. There's no discussion function, groups or anything that makes LibraryThing such a fun place to be. You're also limited to stuff that you've read on the Kindle, rather than all the books that you've had from Amazon, which seems silly to me.
However, it's there. Hopefully they'll expand the use in the future - it's clearly been around for a while as some people have thouands of followers, but equally someone was listed as a 'highly followed person' with 36 people following her. Hardly 'highly followed'. It'll be interesting to see how this is used by Amazon in the future - I can't believe that they're going to leave it as bare bones as this!