"Amish walks into his home office," Microsoft writes in one of many fictional scenarios outlined in the Windows 8 slide decks. "The proximity sensor on his PC detects motion, and wakes the PC. By the time Amish sits down, his PC is powered up. It scans his face and logs him in. Finally, when Amish gets up and leaves, his PC notices that he's gone and locks itself and powers down."
The real-world translation, based on my experience practicing medicine:
Once this technology matures, you'll be required to obtain a Federal Face-Verification Code from the Bureau of Facial Recognition, Division of Passport Control, US Department of State, in order to use a computer once you've registered with, and been granted a license to purchase one by, the Personal Computing Division, Computer Security Administration, Department of Homeland Security.
Your DHS Application for Authorization to Acquire and Use a Personal Computing Device will require a complete list of all intended uses, end-user applications (programs) applied for, cloud storage provider to be used, a fingerprint card verified by your state Department of Public Safety (properly notarized), permission to conduct an FBI background check and access your cloud computing account, and a CRS (Certified Retinal Scan) obtained from your local Passport Office. Once you've satisfied those requirements and paid all applicable fees, you'll be issued a Personal Homeland Security Random Code Generator for your 3-level secure login, and you'll then be permitted to present your license to a designated Homeland Security Certified Retailer to purchase a computer (with Windows 8!).
Once it's been delivered to your home by a Federally-Certified Personal Computing Device Delivery Service and set up by a Federally-Certified Home Computer Installation Specialist, you'll be required to activate your OS by calling a dedicated line at the Personal Computer Activation Service, Microsoft Division, Federal Bureau of Investigation, US Department of Justice, and following the prompts, enter your 25-digit alphanumeric OSIN (Operating System Identification Number), 10-digit Device MAC (Media Access Control Number) and 16-digit Federal Face-Verification Code. If you've made no mistakes, you'll be prompted to get in front of the computer so it can see you and to login to a secure Homeland Security website using an 8-digit access code provided by the AVR (Automated Voice Response) system. A Federal Active-X Control will scan your system & if your face is recognized (the retinal scan is only needed for activities requiring a Security Clearance of Secret or higher) and everything matches with Homeland Security's SDACU (Secure Database of Authorized Computers and Users), it will activate your OS & you're just good to go.
Of course, the above assumes you've already registered your voice with the Voice Recognition Verification Division, U.S. Bureau Immigration and Customs Enforcement, Department of Homeland Security, and paid the applicable registration fee. Otherwise the Computer Activation Service won't recognize your voice and will just hang up on you.
If you plan to use certain software applications with potential security implications (these will be identified in the course of your Application for Authorization to Acquire and Use a Personal Computing Device), you'll need to obtain a Registration Number from the Division of Potentially Dangerous Software, Bureau of Alcohol, Tobacco and Firearms, U.S. Department of the Treasury, in order to use them. Registration must be renewed every two years; initial and renewal fees apply.
Oh, and if your computer is a notebook or other mobile device, and you plan to travel with it, you'll also need to apply to the Personal Mobile Computing Division, Transportation Security Administration, Department of Homeland Security, and pay for a Computing Device Mobility Authorization Card verifying that the notebook is certified safe for transport via commercial carrier, to avoid needless delays at airports and other TSA screening facilities, and to free up TSA screeners for more bra-checks & crotch-fondling.
Windows 8 is gonna be awesome!