The discussion is more about alternatives to using a Java portal strategy, as opposed to simply listing off various other portal products that are competing in the Java space, which is what this thread is more focussed on. Hopefully this added thread will provide a resource to people who are asking this question in a slightly different manner.
The apache project provides Pluto and JetSpeed.
WebSphere is a pretty big player in the licensed portal pool.
JBoss Portal 2.0 framework and architecture includes the portal container and supports a wide range of features including standard portlets, single sign-on, clustering and internationalization. Portal themes and layouts are configurable. Fine-grained security administration down to portlet permissions rounds out the security model. JBoss Portal 2.0 includes a rich content management system and message board support.
An integrated web content management and corporate portal server; 100% Java based; Available under a collaborative source license (contribue or pay paradigm); Installed in minutes; Easy to use and to administer; Full Multilanguage and I18N support; Staging environement; Content Workflow; Content Versioning; Document Management (WebDAV Support); Built-in Portlet-based interface; Built-in support for standardized java web applications and web services (default servlets supported as portlets); Full web-based administration; Integrated with the Apache Lucene Search Engine; LDAP compliant; JSP and JSTL support for easy templates development; Integrated HTML cache engine; dynamic XML export module and much more...
The eXo platform is a powerful Open Source - JSR 168 compliant - enterprise portal built from several modules. Based on the most innovative tools, API and frameworks such as Java Server Faces, Pico Container, JbossMX and AspectJ.
Apache Cocoon is a web development framework built around the concepts of separation of concerns and component-based web development. Cocoon implements these concepts around the notion of 'component pipelines', each component on the pipeline specializing on a particular operation. The Portal Framework is based on Cocoon and is rumored to eventually support JSR-168.
Stringbeans is a platform for building enterprise information portals. The platform is composed of three components: a portal container/server, a Web Services framework, and a process automation engine. Compatible with JSR 168 standard, mobile client support (WML 1.1 and XHTML MP 1.0), JAAS-based user authentication, portlets capable of displaying RSS headlines, multi-page tabular data from database tables, reports, charts, XML documents via XSL tranformations. Stringbeans is deployed as a J2EE Web application in a container that supports Servlets 2.3 and Java Server Pages (JSP) 1.2 specification. EJB support is not required.
InfoGlue is a GPL-based content management and JSR 168 Portal system. Key features includes full multi-language support, excellent information reuse between sites and extensive integration capabilities. A dynamic visual page builder. This release supports advanced workflows as well as very detailed access control both internally and externally.