Hello,
It would be nice to have a way to allow login on a platform (cmsms) with
multiple domains.
Ex: when i login site1 and then go to site2, i am automatically loggedin site 2
as well...

I know there are Session limitations in php... one way would be to use openID.
ex: http://devzone.zend.com/1254/getting-started-with-openid-and-php/