...which you might think turns the computer off (after all, it looks identical to the symbol on the "off" button on my monitor, and PC). But it doesn't. By default, it puts the PC into "Sleep" mode (a fact that admittedly is explained if you pause the mouse over the button for long enough for a tooltip to appear).
It's possible to change this button to an actual "Shut Down" button - I know this because it's the first thing I figured out how to do once I woke my PC from it's unintended slumber. Here's how you do it:
From the Control Panel, choose Power Options. You'll get a window like the one shown below:
Next select "Change Plan Settings" beneath your currently selected "power plan" (if you're in the habit of changing between power plans often, you'll want to make this change to all three of them).
Now, what we want to achieve is considered "advanced", so click on "Change advanced power settings".
In the Advanced settings window, scroll down and expand "Power buttons and lid", then expand "Start menu power button", and choose "Shut down" from the drop down.
Confirm out of all those dialogs, and next time you click on the start button, you'll find that the "Sleep" button has been replaced with a slightly different and a touch more red "Shut Down" button:
If you're wondering what the "Hibernate" button looks like (I did), you'll find that it's indistinguishable from the "Sleep" button, which confirms Joel's theory that nobody really knows the difference between the two!
Don't get me wrong, I do love Vista and have no desire to go back to using XP. But when installing a fresh build of XP there were certain changes I always had to make (such as removing that bloody dog from the Search function or uninstalling MSN Explorer), and I get the feeling that it won't be long before I have a similar mental list of crucial tweaks to make to Vista installations. Thank goodness I don't have to suffer the ignominy of a standard desktop build at my current place of work.
As a professional developer who spends every working day writing software which must meet the differing needs of many different users, departments and even companies within the group, I'm also well aware how an initially "simple" piece of functionality can quickly grow horns and become very complicated indeed. But as Joel says in his final paragraph, maybe we should try to cease the "make everybody happy" approach and instead develop simpler, better, systems that encapsulate the best practice, or at least compromises that everyone can agree upon. It's certainly food for thought.
And now... I'm going to turn my PC off :-)