I was having this problem myself a few days ago, but I got it resolved and pushed the appropriate changes. Specifically, the problem was that two different versions of the JSP API were being resolved from the pom.xml (because the artifact ID was different, Maven didn't know any better and tried pulling both of them). What needed to happen is for neither to be included in the WEB-INF/lib for the app, so I needed to explicitly mark both of them as "provided" scope. I tested this both with 'mvn tomcat:run' and in the tcServer in SpringSource Tool Suite.
How are you running the app? Maven's tomcat:run? STS/tcServer? Something else?
Spring Social Project Lead