TwittyTunes - Post your tunes to Twitter using FoxyTunes, and more...: "TwittyTunes is a FoxyTunes companion Firefox extension - it allows you to post your currently playing songs to Twitter. As a bonus, you can also post the websites you're visiting, videos you're watching and more!"
You should be able to see it in action on my sidebar. I'm listening to The Shins from Rhapsody.com, it is inserting it - along with a tinyurl link to Foxytunes Planet - where you can click and then see a bunch of related content from/about The Shins from YouTube, Wikipedia, Flickr, etc.
Unfortunately, the link isn't clickable from the Flash widget, but if you click through to my account on Twitter, it is clickable there.