Why no power button on keyboards?

but I recall someone on here who used to work for apple's engineering group mentioning that the power over usb on the keyboard was a hack that wasn't as elegant a solution as it was over adb, so it was cut in the second generation of usb keyboards.

That would be Dr. Bob, and yes, it was a hack. And besides, with the placement of power buttons on modern Macs, Apple's stance is pretty much that you should put the machine to sleep when not using it, instead of shutting it down.

Just hold down the Control key and hit the Eject button, and you get the standard "Are you sure you want to shut down your computer now?" dialog box with the Restart / Sleep / Cancel / Shutdown buttons.

Also, did you know that when that dialog box comes up, hitting R is the same as clicking Restart, and "S" is the same as clicking Sleep? Of course, Command-.(Period) is Cancel, and since Shutdown is highlighted, hitting Enter or Return is the same as clicking it.

*edit
This works when the machine is running, of course. If you're starting it up, you gotta mash the big round button.
/*edit

But you can't do that to turn it on!

It doesn't bother me one bit, seeing as my macs never get turned off.

they did it to conform with Industry USB Standards

Yeah, I was interested more in starting up than shutting down. I'm still on my souped-up B&W, so no low power deep sleep for me--the fan is on, sleep or no sleep. I often shut the bugger down when I'm not using it and always turn it off when I myself go to sleep. I'm really impressed by the low power deep sleep that the DA G4 which I just bought my wife does. I didn't realize how low power the new Macs go. That alone, has me itching to upgrade. So how much power is a deep sleeping Mac using?

"Deep sleep" is what Apple calls saving the contents of RAM to the hard disk and shutting the computer down entirely. It uses virtually no power. For regular sleep, the more modern macs pretty much power down everything but the memory and probably some motherboard support chips. I remember that my G3 didn't sleep in the same way that my Mac Mini does.