This new interface is a simple, consolidated place for all your interactions with the USPTO. It is a "personalized homepage and gateway to USPTO business."
It can do almost everything! It provides shortcuts to USPTO applications and other sites, you can link payment methods for one-stop shopping, and the widgets are customizable to meet your particular needs. The default widget collection contains some for general information, as well as widgets specific to patents and to trademarks. One of the most helpful might be the Patent Form Finder, which is both searchable and browseable, for best form finding help. The patent & trademark docket widgets provide notification when there are changes in the applications you are tracking, and they can also send email notifications.
At this point, it is only available for individuals, but access might be extended to businesses soon.