Microsoft's licensing system for Windows 7 has been cracked, using a leaked copy of a Lenovo OEM DVD ISO from which the product key and OEM certificate were extracted. The exploit is apparently sufficient to pass Windows Genuine Advantage (WGA) validation, meaning that anybody with sufficient technical knowledge to implement the hack can get themselves a working copy of Windows 7 Ultimate months before the OS is officially launched.
Microsoft have an unfortunate history of seeing their WGA security tool bypassed by enterprising hackers, and OEM license keys are often instrumental. By extracting keys from digitally-signed OEM certificates and combining them with OEM product keys, a limitless number of activations can be produced; great for a manufacturer building and licensing thousands of PCs, but not so great for Microsoft when that same system is used by software pirates.
The system to implement a false license key is currently complex, but it seems likely that hackers will streamline it into the same style of one-click toolkit that proliferated for Windows Vista and Windows XP before it. SlashGear, of course, does not advocate software theft, and we'd recommend you wait for the official release of Windows 7 in October. Not only is it illegal, but pirated software is often used to distribute spyware and viruses.