There's no confirmed UK price yet, though I'd expect to hear one confirmed later today, so check back. I've contacted Microsoft for more information and I'll let you know when we hear anything.
As a sweetener, Microsoft is throwing in Media Center at no extra cost -- you'll be able to download the media-centric software through the 'add features' option in Windows 8 once you've upgraded.
This is a temporary promotional cost, and will run through to the end of January 2013, assuming Windows 8 survives the Mayan new year.
If you're upgrading from consumer Windows 7, the update can bring across everything, including Windows settings, personal files and apps. If you're currently on Vista, you can import Windows settings and personal files, while those languishing on the delightful Windows XP can only drag personal files onto the new platform.
I'm happy that the cost of upgrading is going to be relatively low, as it should tempt those who otherwise wouldn't bother to give Windows 8 a try, and it's way cheaper than Windows 7 was to start with ($120 for Home Premium edition).
I'd still hoped to see it cheaper, however -- Apple recently set the cost of Mac OS X Mountain Lion at a wallet-pleasing £14, or about as much as two London pints. And would you rather have access to Apple's exciting new operating system, or two jars of beer? Actually, don't answer that.
Will you be upgrading to Windows 8? Let me know in the comments or on our Facebook wall.