Here is my scenario:
We have a main web application written in ASP.NET that uses forms authentication (uses the default asp.net membership and role provider)
We have a 2010 sharepoint portal that is configured to use forms authentication (it points to the same AspNetDB that our main web application does)
We would like to link from our main application (the regular ASP.NET one) to the sharepoint app and not have to re-login. Both sites have the same top level domain and machineKey web.config settings. I figured all of this would 'just work' because the forms authentication cookie would sent to the SP site and it would recognize that this is an already authenticated user. This doesn't work and I am not exactly sure why. I noticed the SP site writes the FedAuth cookie, and I wasn't expecting that.
Any idea's/links/hints. Anything would be appreciated.