Graphic Representation of Musical Genres

I've been thinking about data visualization and their relationships to organizational hierarchies and categorization for a few weeks now. Suddenly this rolls through my inbox:
http://www.musicplasma.com/

Type in an artist or band, and you'll get back an incredibly cool visual representation of relationships & similarities to other artists and bands. From there, you can zoom in and out of and move around in the cluster. Clicking one of the related artists will pop you into a new grouping. What a great way to discover new music based on what you know you like. They've got some pretty obscure stuff in there, too. It wasn't too easy to stump it other, at least with pop and rock. Classical got it all confused.

Unfortunately, I couldn't find any description of how it works. The inter-relationships, based on genre and also time period, could be being pulled from some neat underlying RDF, but that doesn't explain how they track popularity and "representative of a musical style". I love the visual element, but (sadly) would also love a peek at the underlying data structures.

The design's super slick. I like the way you can change the style of various elements. I'm a bit taken aback that Neil Young's bubble is about twice the diameter of Dylan's, though!

Thanks for the link Betsy!