ESBN content IDs can now be used as permalink solutions. URLs change but ESBN IDs do not. Each ESBN ID includes a reference URL in the meta data that can be updated to reflect changing URLs.
To reference your content as a permalink, regardless what your URL may be in the future, simply link to your ESBN ID as illustrated by the following URL:
http://go.esbn.org/esbnid - substitute the esbnid with your own ESBN ID such as:
http://go.esbn.org/73306-060227-650200-43
A special thanks goes out to Michael Clark for this suggestion! Join the (R)evolution and Tag your (C)opyright!