The Genealogical World of Phylogenetic Networks has an interesting post, The Music Genome Project is no such thing.
The Music Genome Project is a database in which 1 million pieces of music (currently) have been coded for 450 distinct musical characteristics. The main use of the database at the moment is to provide the data from which predictions can be made about which other pieces of music might appeal to listeners of any nominated musical set; this is implemented in the Pandora Radio product. This seems like a valuable idea.
What's being studied, however, are "phenotypic" traits. But that's OK. It still looks interesting.
There's also this link to Victor Grauer's Phylogenetic Tree of Musical Style, which is based on the Cantometrics project that Alan Lomax organized back in the 1960s. I've only glanced at it, but it looks pretty interesting.