From the perspective of third party developers, trac provides a useful administration interface from which you can administrate all aspects of your project, from it's description to SVN commits list and file downloads. Trac also has much better milestone and target tracking for bugs and releases.
As a user, you can search the available projects, and use the clean navigation to find your way around. There's also an online SVN browser where you'll be able to look at a project's source code.
Chris is looking to begin converting projects over from the NOC as soon as possible. On request, he can import tracker and SVN history, or alternatively you can start afresh. He'd like to talk to people as he makes the conversion so that if anyone's missing something useful, or has suggestions he can improve the Trac installation for everyone.
Looking to the future, we'll convert the core PostNuke project over to Trac. We'll also try to get single sign on between community.postnuke.com and Trac working if possible.
If you are a third party developer, be aware that we are planning to close the NOC in the future. If you have active projects you should have them converted to Trac as soon as possible. All NOC content will be archived, however due to the ongoing spam issues we will eventually remove the NOC from public access.