The old version of pluto.jar included in these releases failed to support the store() method, yielding telltale stack traces in the log that look like this:

Nested Exception is java.lang.AbstractMethodError:
org.jasig.portal.container.om.common.PreferenceSetImpl.add(Ljava/lang/String;Ljava/util/Collection;)Lorg/apache/pluto/om/common/Preference;
       at
org.apache.pluto.core.impl.PortletPreferencesImpl.store(PortletPreferencesImpl.java:329)

       at
yourpackage.YourPortlet.processAction(YourPortlet.java:82)
.....

This issue is resolved by upgrading to a later pluto.jar

This issue is also documented in a knowledgebase article at http://support.unicon.net/node/565