Twitter Cards (the expanded tweet)
Expanded tweets look cool and are, judging from the examples pretty easy to implement, especially if you are already using Open Graph (Facebooks attempt at an open metadata standard) – an example taken straight from their documentation.
“…You’ll notice that Twitter card tags look similar to OpenGraph tags, and that’s because they are based on the same conventions as the Open Graph protocol..”
I don’t really talk about business politics much, I have a bit of an issue with how Google doesn’t like to play well with others, but it is good to see that Twitter & Facebook are working together in a field that some might consider competitive, I have never really seen the two competing against each other, ones for friends and the other is more for information, Google always wants to compete against both of them and seems to have really annoyed them both in the process!
I am not sure the acceptance rate, but the fact that it promotes your twitter account makes it well worth doing if you have a site that will get traffic from Twitter!