Please read it in continuation of my old stories on choosing open source java portal server. The one was not based on any extensive study but based more on my past experiences with java open source portals. After that a few things have changed. (yes, and will keep changing:-) ) Probably on the same day of my post, GridSphere released version 2.0 of their portal server. eXo has also came up with RC1 of the their portal server. I have given a quick look to eXo but didn't get sufficient time to go through GridSphere.
Meanwhile, Nick also tried to deploy some JSR 168 portlets on different portal servers. But he was not able to deploy it on any of the servers. Primary reason being insufficient documentations. He has chosen GridSphere, Liferay, eXo and uPortal for his experiments. You can read his full post on Java Portal Discussion Forum. Again the study was not comprehensive one but you can say one step ahead in evaluating portal servers. At least you can get some different perspective. What he concluded was as follows -
From my point of view the Gridsphere hot-deploy feature & deployment UI seem nice, but I can't make them work. I had the most success Liferay, but the JSR168 implementation has some bugs. uPortal seems nice, but JSR168 support is badly documented. I'm hopeful about EXO, but so far unsuccessful in deploying to it.