The Windows 8 upgrade offer page is live.
The relevant text of the page states:
We’ve got you covered.
Buy a Windows 7 PC and get Windows 8 Pro for $ 14.99.
Refer to the information below for the offer details.
The offer is for customers (e.g. Home users, students, and enthusiasts) who purchase a qualified PC. A qualified PC is a new PC purchased during the promotional period with a valid Windows 7 OEM Certificate of Authenticity and product key for, and preinstalled with:
- Windows 7 Home Basic;
- Windows 7 Home Premium;
- Windows 7 Professional; or
- Windows 7 Ultimate.
The promotional price is limited to one upgrade offer per PC purchased, and a maximum limit of five upgrade offers per customer.
You can get to the page here.