is "bsf-2.3.0.jar" the same file as this one: http://www.findjar.com/jar/bsf/jars/bsf-2.3.0.jar.html
If yes, I assume that the "taglib.tld" file inside is wrong. It declares this URL: "http://java.sun.com/j2ee/dtds/web-jsptaglib_1_1.dtd"
But it should be: "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd"
If you fix it in "bsf-2.3.0.jar", it should work. JBoss already bundles the necessary DTDs and XSDs (in \jboss-6.0.0.Final\docs\dtd\)
Hope this helps