Portal runs on top of the WebSphere Application Server, and has a significant price tag attached to it.
JSR168 and JSR286 are portlet specifications that go beyond
Servlets and JPSs, allowing for the development of small 'content spots' or 'portlets', and these are deployed to a portal server.
Facebook or Yahoo.com provide 'portal-type' of experiences, with many small and different content windows being assembled on a common page, along with the ability for different users to highly customize their personal experience. While Facebook is different in technology to portal server, the experience a portal server is intended to provide the end user is similar.
-Cameron McKenzie
