James Robertson of Step Two Designs recently published an excellent article on portals. As usual, James has a very pragmatic and even perspective in evaluating the business value of the technology. In addition to helping to define the term "portal" (I would say that over half of the projects that I have worked on that were initially described as portals were actually not portals at all.), the article reminds us that portal integration is only one click deep and is not a silver bullet to the enterprise information problem. But, if executed properly, there is business value in having a central place that summarizes information managed in different places.
One peculiarity that I did notice, was that Jame's definition of customization and personalization are the reverse of what I am used to hearing.
Personalisation allows individual users to tailor the portal for themselves (such as what information is displayed).
Customisation involves the filtering of information and tools to target identified user groups or roles (such as delivering information to specific geographic areas).
Must be a hemisphere thing.