At the following link you will find jetspeed/portlet related documentation and related work I had done some time last year.

I am not sure how much of this stuff is still relevent in portlets.

/akc/servlet/DisplayServlet?url=NotesURL&ownerUserId=satya&folderName=Java-Portlets

Additional references

1. How to use aspire portlet

2. Source code for aspire portlet