When Windows 95 was launched, one of its most important changes over Windows 3.11 and earlier versions was the inclusion of an entirely new graphical user interface. At the very heart of this interface and the Windows 95 marketing campaign was the Start menu and the button that activated it. In the Windows 8 Consumer Preview, to be released at any moment now, the Start button is gone.
The Consumer Preview has already been leaked all over the web, and it has been confirmed that it no longer contains the Start button (or orb, since Vista) or the Start menu. This is actually not all that surprising, considering the start menu's functionality had already been reduced severely in previous beta releases. Now, it's gone completely, with the Windows 7 taskbar in Windows 8's desktop mode now acting solely as a taskbar.
The Verge has confirmed with its sources at Microsoft that the start button has been replaced by a hot corner (for mouse operation) and a gesture (for touch) which essentially serve as a means to switch between the Metro interface and the traditional desktop. On mouse activation, a thumbnail will appear of the mode you're switching to (Metro or desktop).
The decision is supposedly not entirely final, and there's a minute chance that, given enough feedback, the button might return. Still, everything is pointing towards the full death of the Start menu and button. Let's face it - 17 years of service is an eternity in the computer world, and in all honesty, I do feel somewhat sad for its demise.
For many, it's a cornerstone of computing, and now it's gone. We need to come up with a new "press start to shut down" joke.