PostNuke is a Pretty CMS !
PostNuke is a strong and distensible CMS.
You can build a portal website very easy based on postnuke.In my view,Postnuke is like eclipse.the kernel of postnuke is just a framework or some criterion.And the main functions is like so many toy bricks based on the groundwork.And postnuke is a opensource software,it is complete free.So there are so many thirtpart modules for postnuke.
You can develop postnuke modules either.