It's a new "feature" of the software called the activity stream, and it does seem a bit different than what we had.
So if you click on the "What's New?" link you are taken to the activity stream. There is a second smaller navigation bar under the main one with these on it - Activity stream, new posts, new group messages, and unanswered threads (I just added this one).
Are you looking for the "new posts" link? If that make more sense then I could make it the default when we click on the words "what's new".