Yes, and I do not like this change at all. I find myself accidentally pressing this button on multiple occasions. The previous behavior would present you with a dialog, allowing you to choose your action. (cancel in most of my cases) Now my display powers off constantly and requires me to enter my password to get back in. I wish there was a way to get back to the previous behavior.

I thought it puts the computer in sleep mode, which would be a nice shortcut. But it's only the display? looks like I'll now have to use the control + power button then click on "sleep". With a second display, closing it to sleep won't work either.

Holding the button for 1.5 seconds will present the older-style "restart/shutdown/sleep/cancel" dialog.

Holding for about 30 seconds---on any Mac or OS version---will force the computer off.

It's only about 5 seconds, not 30, to get a forced shutdown. They might have changed it on the newest-gen Airs, but around 5 seconds or so has been the standard on every Mac for many, many years.

If anyone finds a way to tweak this (unlikely with the demise of the defaults system), I'll be indebted to them forever. I hit that button all the time to bring up the power options dialog, and it's been driving me utterly insane. It's also annoying when a baby or cat gets to your computer - one button and boom! It's asleep. Grrrr...

I agree! If anyone discovers a way to disable this “feature”, I’d really appreciate it too. On the MacBook Pro Retina, the power button is a regular keyboard key positioned right above the [delete] key. I run PowerPoint presentations at corporate events and if I accidentally hit the power button, it would make the projectors go black for a few seconds before I realize what is wrong, wake the Mac up and log back in.

On Windows computers, you can choose what pressing the power button will do: Do nothing, Sleep, Hibernate or Shut down. On my Windows laptops that I use for corporate events, I have them set for “Do nothing,” even though the chance for me to accidentally press them on my Dells is much less than on my MacBook Pro Retina.

Totally empathize - this seems like one of those changes made for change's sake. I mean, if you have a laptop and want to put it to sleep... CLOSE THE LID! Why do I need a button to perform the same function? And how many iMac/mini users are reaching around behind to do that?

This actually used to be default behavior on (desktop) Macs years ago. I suppose the behavior was slightly different for laptops - but I've mostlu dealt with towers and iMacs over the years.

And even before Mavericks - you can power down any Mac OS based system by holding the power button for an extended period of time. Hell - same thing goes for Win-based computers.

Is the longest push a forced shutdown?

Yes, if you hold it down for about 5 seconds, it is a forced shutdown. Don't do this unless the computer is completely frozen.

First, a confession that I'm still using Snow Leopard.

I've been using the keyboard shortcuts of Option+Command+Eject to put my Macbook Pro to sleep, and Control+Eject to bring up a power window with Restart, Sleep, Cancel and Shutdown as choices. Am also giving strong consideration to making the plunge to Mavericks but am unsure of whether any of the above shortcuts will still work.

Would anyone care to verify?

Yep, those shortcuts both work the same in Mavericks.

Using the Control + Eject...or the Control + Power will still bring up the ole standard dialog box instantly.

@ diamondsw: in the meantime you can just use Control + Eject, this combination will bring up the power options dialog immediately.

5 seconds is a forced shutdown, this should NOT be used unless absolutely necessary. But thanks for the 1-2 seconds hint. I didn’t try that and was also annoyed by the new behavior. Now I do not need to use ctrl-eject anymore.

This was a bad and unnecessary change, especially for laptops, which represent the bulk of their sales. Laptops already go to sleep when you close the lid, and we are all already trained to force a shutdown by holding down the power button. Now we have to train ourselves to hold it down --- but only just so long, or the system will do a force shutdown. Bad bad move. Someone, please please please find a way to restore the original behaviour.

Excellent, minor change but a good one :)

The behavior for the power button seems oddly familiar.

Clicking the power button on and off - Turns the screen on and off
iPhone's sleep/wake button has the same behavior.
Holding the power button confirms Shutdown - or Power off confirmation on iPhone
Holding even longer forces shutdown on Mac or reboot on iPhone

Clearly this is the "Back to Mac" effect happening in Mavericks

This is a very Apple move people.

The old key combination to quit all was 'command+option+control+eject icon'. Since the new Mac Book pros have no eject button. So maybe someone with a new Mac Book Pro could experiment with 'command key+option+control+power button' to see if quit all apps and shutdown. Would someone try it?

Good news! With the latest 10.9.2 update, Apple seems to have fixed how the power button reacts to presses. The MacBook no longer goes to sleep with a quick accidental press of the power button. You have to press and hold the power button for 1 second, then release it and the MacBook will go to sleep. If you press and hold the power button for 2 seconds, the Restart, Sleep, Cancel, Shut Down dialog box appears. I didn't try it, but I'm sure if you continue to press and hold the power button down longer than 2 seconds, it will do a hard shutdown. Yay!

http://hints.macworld.com/article.php?story=20140305140635280