Are you talking about the helloworld example at http://labs.jboss.com/file-access/default/members/portletswap/downloads/portlets/samples/HelloWorldPortlet.zip?
If so, the build.xml mentions a .ear file but it really doesn't build it. If you look at the directions in README.txt with this example, it states you can "hot deploy" by dropping the WAR file in the appropriate directory. This means you simply have to build your NetBeans project and drop the WAR file in the necessary directory for a hot deploy. Of course then you'll have to use JBoss Portal's UI to define it in the Portal.