I just installed an update to vBulletin 4.2.0 so things may look/act a little different.
For one, if you're used to click on 'What's new' (which used to be on the right - now far left) and seeing the latest posts, now if you do that you will see an 'activity stream'. Then under the Activity Stream Tab, you will see a small link that says 'new Posts' which brings you back to the 'old' screen of latest posts.
(though on some other pages you may directly see the 'New Posts' link as well)
Also updated Tapatalk, so for those using that, let me know if that gives you any issues