Canada, USA, Japan promotion ends July 11.
Europe promotion is selling the full retail editions for slightly more than Upgrade in USA, and it starts July 11.
Windows 7 Home Premium Upgrade Edition (requires activated XP or Vista install, but allows clean install once it confirms) is US$50, CAN$65 at Best Buy and Amazon. Regular price will be $120.
Although it is called Upgrade, you can do a clean install with it, but you have to install and activate XP or Vista first, so it can confirm you are already a customer. It will then give you the option to wipe your machine and do a fresh install.
Why is this relevent to gaming?
Windows 7 will have DX10 and DX11, matching or exceeding Vista's gaming functionality, but with less bloat. Windows 7 is less of a resource hog than Vista, and runs much better on Netbooks. Windows 7 uses a newer revision of the Vista driver model, but isn't a dramatic redesign like the jump from XP to Vista, so anything that works in Vista currently will work in Windows 7.
The promotion ends July 11. For people who have high end machines still running XP, this is a great price for access to DX10 and DX11, along with a quality 64-bit OS (you can pick 32-bit or 64-bit, both on same DVD).