Blip.fm is "Twitter for music" as it offers a microblog platform for users with the ability to search, upload and share music. Your blip.fm stream is then playable. You can also discover music from other Blip.fm users and give them props if you like a song they played.
I first discovered Blip.fm a month ago and I looked at it and liked it. I just rediscovered and I have to say I like it. Though I don't know if the music available is being distributed with the correct rights, etc. It offers an easy way to find song and artists you like and play them from the page. You can also embed them into your page and share them with other social products like Twitter, Last.fm, Tumblr, FriendFeed and a few others. If you are on Blip.fm - we should friend up.
Word on the street is that Blip.fm is growing like a weed and is looking for a little funding to keep this good thing going.