IMHO, Jetspeed is only a good solution if you have a dedicated staff or contractor(s) willing to get VERY intimate with the code - and who are very smart on the Jetspeed supporting technologies. Numerous people have requested examples of "real" portals being hosted under Jetspeed and I think the best we've seen are one in Australia and one in... Indonesia? (Check the Jetspeed home page.) I've seen several queries related to more than trivial security control receive no replies on this list.
Certainly the technologies underlying Jetspeed - Java servlets, relational DBs, etc. - are well understood and proven. As you mentioned, Jetspeed code (at least an old version) is incorporated in IBM's Websphere, and you can't get much more industrial strength than that. However, the Jetspeed documentation is spotty at best; there are NO books available on Jetspeed, so expect to spend a LOT of time deciphering the code, structure, interrelationship of the various config files, whether or not various config parameters actually work, etc. Other open source portal solutions that might be worth looking at include uPortal (http://mis105.mis.udel.edu/ja-sig/uportal/) which is developed and controled by a consortium of universities, or Zope (http://www.zope.org/) if you're willing to step out of a Java-centric product. I think Jetspeed is going through a lot of growing pains. It is a 1.x product after all. There is certainly a lot of good work being done on the product, but I think once you get into more sophisticated needs - reasonably complex security for example - you'll find it requires a lot of tweaking and development of custom code to get your work done. If you're not afraid of that, then go for it. - Jasen.
