This happens with Win7's start search. Considering that many power users use start search without the mouse (i.e. hit windows key, start typing the name of something, hit enter) it's a really bad implementation.
The Mac equivalent (cmd+space to trigger spotlight, start typing, hit return) behaves as it should. If you move your mouse it'll highlight what is under it, otherwise the highlight stays on the top result as you type.
The Mac equivalent (cmd+space to trigger spotlight, start typing, hit return) behaves as it should. If you move your mouse it'll highlight what is under it, otherwise the highlight stays on the top result as you type.