An updated version of JSON-taglib has just been released. The new version includes a number of bugfixes and improvements, including improved error messages and support for running within a JDK1.4 environment.
This release also includes a completely redesigned project site.
http://json-taglib.sourceforge.net
Full details of the changes can be found in the project change log:
http://json-taglib.sourceforge.net/changes-report.html