JSP EL that worked on JBoss AS 4.0.5.GA does not work on EAP. For example, the following does not work:

<c:set var="truevalue" value="true" />
<c:set var="falsevalue" value="false"/>
<c:out value="${not empty param.yes?truevalue:falsevalue}"/>

It throws this error:
2009-06-11 10:40:57,487 ERROR [org.apache.catalina.core.ContainerBase] Servlet.service() for servlet jsp threw exception
org.apache.jasper.JasperException: /jsp/case305721.jsp(27,3) "${not empty param.yes?truevalue:falsevalue}" contains invalid expression(s): javax.el.ELException: Error Parsing: ${not empty param.yes?truevalue:falsevalue}
at org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:40)

But this works with a space added before the colon:
<c:out value="${not empty param.yes?truevalue :falsevalue}"/>