The ability to pull up multiple posts on a single screen, for instance in reading a person mark's unread posts,
I just checked and it already works that way.
You can click "Read Last 50 Messages" in a person's profile, or if you click their number of unread messages on the Favorites page, it'll display all of the messages on one screen rather than stepping through them one at a time the way SI does.
I'm sure both of those only work for Premium members, and you are one.