Nothing groundbreaking here but I thinks its worth showcasing visually:
Spotify yesterday promoted their embeddable play buttons and playlists via Facebook and Twitter yesterday. Those 'widgets' can appear on sites, blogs, etc and play in-line much like it works on Facebook within the newsfeed / ticker.
Those tweets are then embeddable as well - and you have started to see more and tweets appear in-line within stories, blog posts, etc. As Twitter content becomes more and more of a starting point for conversation (on and off Twitter), those embeddable widgets are terrifically useful.
And back to the Spotify post: notice the Facebook Social Plugin (right column). So the main post shows in-line playlists and play buttons - and the right column shows MY Facebook friends and their recent LISTENING activity within Spotify (on Spotify.com, on Facebook, and now through the web).
Big, virtuous cycle. And an example of Spotify, Twitter and Facebook moving beyond their .com homes.