Partially because it wasn’t obvious to me where to find it, but mostly because it’s cool
Here you will find monthly dumps of Discogs Release, Artist, and Label data. The data is in XML format and formatted according to the API spec: http://www.discogs.com/developers/
This data is released under the Public Domain license: http://creativecommons.org/licenses/publicdomain/
And funny how we just have to rediscover some things.