My university has a large number of legacy applications that we want to provide access to from the portal. Can I do this?

Maybe. It depends upon the application. Did you write the application (and have the source code) or did you purchase a binary package from a vendor? If you have the source code, its relatively easy to create an alternate user interface to the application that operates within the portal. in uPortal parlance, this would be called a "channel". Your channel would display itself to the user in the portal and feed the input from that user to your application. Your legacy application would then process the data and send the output back to the channel, and the channel would in turn display the results to the user inside the portal.

If you purchased an application from a vendor, things are a bit more complicated, but the high-level approach is the same. You'd have to write an adaptor that would wrap the output of the legacy application in XML so that it can be displayed inside the portal. When you have this, you can then write a channel for use with the portal that interacts with your adaptor and actually facilitates the translation of the XML so that the portal can display it.