I want to use CC for user integration with WPMU Membership. What I want is that user only go to one place of my site but get register to all places like (email subscription , user registration etc).
So is it possible to integrate both plugins ?
Constant Contact does have an open API that can be integrated into almost any product or plugin. I'm not familiar with the WordPress plugin you mentioned, but it's definitely possible to do an integration. The only question will be, is this something you could do yourself using their plugin and modifying the code or do you have to go through the wpmu.org team to have them add that to their plugin.