Mannheim University Library recently announced that it releases its catalog data under a CC0 licence.
Translating part of the announcement:
After Mannheim University Library was the first German library to publish catalog data as Linked Data (…), both the original raw data and the RDF version are as of now also published under a CC0 licence and therefore available for anybody to reuse without any restrictions.
The data is available via http://data.bib.uni-mannheim.de/. A CKAN entry for this data set has yet to be made.
It is good news that Mannheim University Library which is experimenting with Linked Data for some time now also took the step to open up the data. Our congratulations on this move. May more libraries follow suit.