Anonymous Portal with Personalization and SSO

My customer would like to serve portal content without forcing the user to log in. I understand that you can serve anonymous content through the EP. My question is:

- If a user has previously logged in to the portal at some time in the past (and then they closed the browser, went home for the night, etc), is it possible to serve personalized content to them without having to log in? The example I would like to emulate is that of Amazon.com. Amazon places a persisten cookie on my computer so that whenever I go back to Amazon.com I see "Jack's Store". The only time I have to login again is when I want to do something that requires security such as "checking out". The problem is that our portal allows for single sign on to other applications. So, while it's perfectly acceptable for someone to browse to our portal and see things like project news (personalized) - I still want them to have to authenticate if they click on the single sign-on links if they haven't given their password in the last hour. Is this possible?