Sigle sign-on feature?

We are considering yo use Idea Informer to gather user feedback for our website knowing who is sending the feedback. However, we do not want to ask an already authenticated user to login again. Therefore we would like to have a single sign-on feature so we can integrate IdeaInformer authentication to ours.
This is already implemented by competitors. One example is GetSatisfaction (http://getsatisfaction.com/help/fastpass-single-sign-solution)