Chris already answered you:
http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4133361#4133361

A portlet is a specialized web application. Almost anything you can do with a web application you can do with a portlet. In particular, this includes accessing a remote web services. Portal forums won't help you there as it's not a Portal topic, rather a web service development topic. In essence, you would need to create a web service client that could be accessed via your portlet and possibly interacted with.