PORTLET and AJAX

Asynchronous Rendering of Portlet Content With Ajax Technology:

http://developers.sun.com/portalserver/reference/techart/asynch_rendering.html

Best Practices for Applying Ajax to JSR 168 Portlets:
http://developers.sun.com/portalserver/reference/techart/ajax-portlets.html

Using Ajax with WebSphere Portal:
http://www.ibm.com/developerworks/websphere/library/techarticles/0606_bishop/0606_bishop.html

Building an Ajax portlet for WebSphere Portal:
https://www6.software.ibm.com/developerworks/education/websphere/0608_bishop/section8.html