It is now available for download from Sun site.
According to Sun, "...It is the world's first freely available, open infrastructure Software platform. Building on the success of our Solaris Operating System (OS), Sun is making its Sun Java Enterprise System, Sun N1 Management software, and Sun developer tool products available at no cost for both development and deployment.
Integrated with the Solaris Operating System, this collection of software known as the Solaris Enterprise System, is the only comprehensive and open infrastructure software platform available immediately..."
You can download Solaris System Enterprise here