I am going to be creating a site that seems like it requires a blend of a content management system (CMS) and some custom web development (which is done in ASP.NET MVC). I have plenty of web development experience to understand the ASP.NET MVC side of the fence, but, I don't have a lot of CMS knowledge aside from getting one stood up.

Right now my biggest question is around integrating security from ASP.NET with the CMS. I currently have an ASP.NET MVC site that handles the authentication for multiple production sites and creates an authentication cookie under our domain (*.example.com). The page acts like a single sign on page since the cookie is a wildcard and can be used in any other applications of the same domain.

I'd really like to avoid having users put in their credentials twice. Is there a CMS that will play well with the ASP.NET Forms Authentication given how I have these existing applications structured?

As an aside, right now I am leaning towards Drupal, but, that isn't finalized.