On at least the News / Activism page, when I hover my mouse cursor over the new search box and left-click, a yellow box magically appears that includes a dropdown menu that allows selecting between keyword, users, titles and Yahoo for your search parameters. It does this for me on my Win XP Pro system with IE as well as Opera; I haven't tested with other browsers. I'm assuming that it's a Flash thing, so if people don't have that installed it may not appear. I'm no programmer so don't take my word on that aspect of things though.
From a GUI standpoint (which I've done for over 25 years now), that's called "information hiding", and is considered a no-no (although it's done all the time). While this allows a window to be uncluttered, it also keeps you from seeing what's going on. Most folks like to have their controls all laid out for them whether they're in use or not -- witness how many folks dislike having to know to right-click on things to see options that otherwise you wouldn't even know existed.
It's like driving a car where the instruments and controls appear when you hold your hand near them, and are invisible otherwise. Not many buyers for that.