Collaborative playlists are a great idea that often gets bogged down and limited by the fact that everyone has their own music service/platform of choice and there is generally no interoperability between them. Fred Wilson blogged on the topic, and the challenges, about a week ago. The problem is that most collaborative playlisting options require a lot of overhead... either everyone needs to join/use/switch to the same playlisting site or the creator of the playlist has to engage in a lot of manual labor to curate the playlist.
I talked a bit recently about how some service are already set up to handle the exact use cases that people are interested in, just that the other pieces of the puzzle haven't been put in place yet. By using the "web as the music catalog", listening data as automated search queries and free-range MP3s as the universally supported format, it is actually easy to create collaborative playlists with a combination of existing technologies that can all work on a common platform. Hashtags, Twitter Search (aka Summize), friendP3 and playTwitter.
To create a collaborative playlist, one just needs to manually post (or retweet a friendP3/meP3 link) with a playlist name as a hashtag. For example, I just started one with the name of #fp3Bestof2009 (where "fp3" stands for "friendP3"). I posted a couple of songs, and others can as well without any overhead required by me to manage. To see the collaborative playlist, I can use Twitter Search to search for that hashtag/playlist name.
Click on the playTwitter bookmarklet and you are off and listening to the community programmed list that continues to be dynamic over time. If you want to filter the playlist, you can simply use the "advanced search" fields of Twitter Search and you can limit posts/songs by contributor, date, keywords, and more. Find a filter you like, and then you could subscribe to the RSS feed for those filters and just watch what continues to come in from users across the web.
User friendly? Uh... nope, not yet. Powerful? I think so. What do you guys think?