MusicBrainz “is a community music metadatabase that attempts to create a comprehensive music information site.” They’re collecting information about music so that your CDs and MP3s can be easily identified and tagged with correct information.
The MusicBrainz Wiki has lots of information for users and developers and so on, and there is a page about FRBR. Here’s s the history section:
Despite this spec being almost a decade old, nobody in the library world has really implemented it yet. It is on the verge of becoming the “flying car” of library catalogs, a utopian dream never fulfilled. The [WWW] Library of Congress catalog is still structured as a bunch of MARC records, which is little more than a 1960s digital equivalent of a 19th century card catalog. One reason for this delay is that FRBR doesn’t specify who is going to do the job, it only says how it ought to be done. (And then the Y2K bug and dotcom crisis got in between.) Traditionally every library has a catalog of the books it owns. The idea that information about books (bibliography) could be separated from the local inventory was all new to libraries in the 1960s, when cooperative institutions like OCLC were born. With time these co-ops have started to act more and more like private monopoly suppliers that libraries depend on but really hate. Here, have some bibliographic data, the first samples are free, then you have to pay your soul, and we will supply your institution for the rest of its life. Throw in a lifetime subscription to the Encyclopædia Britannica as well.
Enter the 21st century and Wikipedia. The common knowledge needs not be owned by a monopoly supplier. Every private music collector and library can keep their local inventory in the shape of links to existing, shared information at MusicBrainz. Find an error, fix it in the shared pool, not in your local inventory. This is how OCLC and Gracenote work. Except that no single entity owns Wikipedia or MusicBrainz, because the contents can be copied freely by anybody. This answers the who question.
Fortunately, Wikipedia and MusicBrainz were created not by the tired old people who wrote the FRBR specification, but by fresh minds from the filesharing generation. Even if this means some shortcomings in the initial data model (just albums, tracks, and artists), leaving plenty of room for improvement, the important difference is that they are getting the job done, as opposed to just theorizing about it.
The last section on the page is about applications in MusicBrainz, and anyone interested in FRBR and music will want to read it.