From the MusicBrainz changelog, a much needed feature update:
The official "permanent" way of linking to HTML web pages for MusicBrainz artists, albums and tracks is now like this, using the 128-bit globally unique identifier (GUID) values:* For artists: http://musicbrainz.org/artist/GUID.html
- for example, http://musicbrainz.org/artist/83d91898-7763-47d7-b03b-b92132375c47.html is Pink Floyd
* For albums: http://musicbrainz.org/album/GUID.html
- for example, http://musicbrainz.org/album/25fbfbb4-b1ee-4448-aadf-ae3bc2e2dd27.html is "Dark Side of the Moon"
* For tracks: http://musicbrainz.org/track/GUID.html
- for example, http://musicbrainz.org/track/7fef22bd-76aa-4803-b56b-93a5d6e70662.html is "Money"