There's no way they'll change the layout of the titlebar widgets for every window. For example, it would only work with applications with a toolbar; windows with just the titlebar have no room for vertically-oriented buttons, and it also removes the text from the titlebar, and that obviously won't do for Safari or pretty much any other application. However, the colour of the widgets (brighter, more glossy buttons), window gradient, check boxes and scroll-bars could be implemented system-wide in the next release of OS X.