JSR-286 has been signed off! Here comes Portal 2. I don't know of any implementations yet... so we are still waiting to play with it.

Portal 1 Challenges
There are a number of pain points of portal development which include:

1. Accessing resources... this is an issue with security mainly
   
2. Portlet to portlet communication through the server framework
3. Ajax communication.
   

Much of these issues have been addressed through the specification...

What's new in Portal 2
First, Portlet to portlet communication is not as cumbersome and isn't limited to some session hacking. The specification provides 2 mechanisms for communication at the server tier.

1. Events
2. Public Parameters

Events that are provided by an event producing portlet are described in it's XML file. Event consuming portlets describe what events they can consume, then at deploy time or run time the portlets are wired together through an event channel.


Second, resources are finally part of the picture. In the portal 1 days, you would often need to access a resource outside the portlet... well this request didn't have any portlet details, such as window state or portlet perferences and worse... it didn't run under the security of the portal.
Now resources are obtainable within the context of the portal. To a certain extent this provides us now with the ability to do ajax style development which wasn't possible before.

Next, there is the standard web page needs which have been addressed. For instance, because a portlet doesn't own the page, it really can't participate in provide header information... until now. There are multiple respond phases now... one for the header and one for markup. This provides the ability for a portlet to participate in the creation of the page header. Additionally access to cookies and other web oriented needs have been opened up.

On top of this their are portlet filters and portlet url listeners...

If it is not too late... the portal world is about to get a breath of fresh air. Take a look at the specification, it is worth a look if you are in this space. Perhaps when the reference implementation is out... and I have time I'll create a demo of a few things... of course I'll need to include some of the latest spring stuff in the mix. It looks like Spring 3.0 intends to have Portal 2.0 support. As I scan around on the web... it looks like liferay is portal 2 ready... maybe it is time to switch back :)