The "ShowSource.jsp" page (used to show the source code of the JSPTL example pages) uses file I/O to read the source page. This causes an Error 500 when the JSPTL examples webapp is run directly from a WAR file rather than being unpacked into a directory. ShowSource.jsp should use the JSPTL "import" tag to read the page source, which will work whether the app is packed or unpacked.
Fixed - thanks, Craig.