The root of the issue lines in:
Shindig uses xercesImpl, xml-apis, an xmlParser which conflicts with JBoss 5.1.0. However, Tomcat needs those files. So we created a new property in liferay-plugin-package.properties called "deploy-excludes"
This property will include an excludes pattern of files which will NOT be deployed to the app server (even though they are in the packaged WAR)
"deploy-excludes" will be for all app servers
"deploy-excludes-xxx" will be for a specific app server (tomcat, jboss, geronimo, glassfish, etc.)
For OpenSocial specifically, I added: