What is the difference between JetSpeed and WebSphere Portal?
I also wanna know the difference between those portal projects: Jetspeed-1, Jetspeed-2, Pluto and WSRP-4J. There are lots of portal projects, however, why the same organization will need to develop so much projects for portals?
What is the additional value of commercial portals?
One obviously value is, say, if you use IBM portal, when you encounter problems, you could seek help from its technical support, or even on-site support. However, if you use open source, Apache wont help you to solve your difficulties within a short period, or even you need to find out the solution yourself.
Different vendor would make their IDE to support its own portal development, but they might not consider to support open source product, unless the product is very popular, like Struts.
Also, as the vendor portal is aims to be worked on its own portal, each vendor might have fine tune their portal component integration, and make the best performance. If you put in, say, Jetspeed or Pluto, into WAS, it might not as good as they worked with apache projects.