The trouble with this apparent generosity is that once you accept an invitation to enter a portal you may never leave. That's because all the portals from companies such as IBM, Microsoft, Oracle, BEA, Sun and anybody else that sells an application server is tied to that platform. That means once you standardise on their portal, you are practically locked into their platform for eternity.
Portals in general are a good idea, but the original purpose of this class of software is being perverted as the major enterprise software vendors try to make the portal the next great user interface war.
Originally, portals were a thin layer of software that allowed users to access any number of applications from the same basic user interface. This was a big breakthrough because, previously, users had to master different interfaces and corporate developers had to support multiple presentation layers on top of their applications.
But once IT started to embrace portals, the threat to the established order of things became clear. Portals essentially divorce the presentation layer from the applications and the operating system, which makes the client interface on top of Windows less relevant. In addition, vendors such as IBM, BEA Systems, Sun Microsystems and Oracle have begun to seize the portal as a way to usurp Microsoft's dominance of the desktop. Microsoft, meanwhile, responded with its own SharePoint offering as a way to combat this new threat to the empire.
The problem is that all these vendors are warring over IT accounts like nation states trying to expand their empires, which basically means colonising IT shops in the hope of exploiting portal sales to sell all manner of enterprise applications. After all, it's pretty clear that portals are going to be the primary vehicle through which web services and any number of collaborative applications will be delivered. So what started out as a common user interface for disparate applications is now the front line in the war between Microsoft, IBM, Sun, Oracle and BEA.
With that in mind, the best thing you can do the next time someone offers to bundle in a portal is just say no. They are trying to get you addicted to a user interface that will make your IT organisation subservient to their middleware.
Instead, take a hard look at the smaller companies in this space. Not all of them are perfect yet, but they offer a thin layer of enterprise software that allows you to keep all the major vendors honest because you can apply it against multiple application servers. And the good news is that there are now standards emerging so any of these portals should be able to sufficiently integrate with any set of applications regardless of the platform.
So by all means, go through that portal. Just make sure the key to the door stays firmly tucked away in your pocket.