Since im forced to use twitter now 🙂 I want to sync my last.fm with twitter: you can use the “Recently played tracks” feed and Twitterfeed. First, create (if you haven’t) an account on Twitterfeed and click on “go to my twitterfeeds (or create a new one)”, then on “Create a new feed”. On that page, enter your Twitter name and password (you can click on ‘test twitter authentication’ if you want to) and on “RSS feed url” type your “Recently played tracks” feed and click on ‘test rss feed’. On “Update frequency” and “Post up to X new updates each time”, you can choose how frequently (and how many updates) you want your tracks to be shown up, but remember to be considerate with your followers, since if you set this to update every 30 mins 5 new updates, this can be somewhat annoying to others. Then on the “Include” drop down menu, choose “title only”, so in this way, you can tweet the direct link to the song, and not only to the musician. Don’t forget to check the box next to “Include item link”. When you’re finished, click on “Update”, go listen to music and see if it works (it should be in a short time) Hope this helps you.
Found at http://getsatisfaction.com/twitter/topics/last_fm_on_twitter