Pardot has always had a public preference center to which you could add certain lists. While this is great for most companies, organizations that sell multiple product lines or sell in different countries have a need for multiple preference centers (e.g. one for US clients and one for German clients).
You can now set up as many preference centers as you would like. You still designate which lists you want to be public and give them labels the way you did before (Go to Segmentation and then edit the lists in question). Then go to Emails and click Email Preference Pages. You can create a new page and add or remove lists that you would like to include in it.
You will still use the same variable tag (%%email_preference_center%%) for your default email preference center. For any custom preference centers, simply use the direct link to the page you create.