Recently, WebsitePanel has released stable version 2.0. This is has fixed many bugs and included the support for new applications like SmarterMail 10.x etc. It has also included the support for Windows 2012 server and SQL 2012 server.
WebsitePanel 2.0 requires .Net framework 4.5 and this is not supported in Windows 2003 servers. If you are running Windows 2003 server, you will not be able to upgrade your WebsitePanel version. Also, as per WebsitePanel developers, there is known problem in WebsitePanel server for Windows 2003 server so you cannot fully manage your Windows 2003 server even if your portal and enterprise components are on different servers.
Since, Windows 2003 server operating system in outdated, we really doubt any further development or support will be availble in WebsitePanel.