From the Kotaku article:
"After hooking up the Xbox One and powering it on, Weingarten was prompted to connect to his home Internet, and then set up his Kinect 2.0. There didn't appear to be any way to back out of that. After connecting to the Internet the console began pulling down a 500-megabyte day-one update, which will be necessary to play games."
Since the out-of-box Xbox still has DRM enabled, you must have an internet connection to boot up. Then, you are required to download and install a 500MB update to get rid of it.
May seem trivial to some of us, but a large amount of customers are going to be confused by this.
Won't be able to play games out of the box? Reminds me of this: