We need to build Content Management System!

Every company needs them. Every company wants them. Every company want to spend money on custom Content Management System that they can call their own. -->

Next time you try to reinvent CMS stop and first take a look at existing CMS systems that very liberally licensed. If you cannot use them at least take a look at their architecture. It will give you a good starting point.
I was just concentrating on the CMS that based on ASP.NET and had a good web presence and documentation.
After some review of architectures Cuyahoga is leading this list for me. N2 is very close behind the Cuyahoga as of March 02, 2008.
When new frameworks come in to play I will review them and reassess.