[brianwhitman]

Right, ISRC is somewhat useful for glue but is not in wide enough use that it covers the world of music. It also reflects "recordings" not "songs" which actually cause a lot of resolution issues (radio edits, clean vs. explicit and etc.) It also does not help anyone resolve artist names like "The The" when their stopword list turns that into an empty query :)

[jdunck]

This is actually the same issue ISBN faces - it does not refer to a work, but a specific printing, binding, etc.

It is the reason xISBN exists. http://www.worldcat.org/affiliate/webservices/xisbn/app.jsp

Ideally an ID cross-reference would be an open dataset, but it is difficult to achieve that in the market. A proprietary xref is better than no xref.