Microsoft detailed about the Windows 8 editions. We already know that Windows 8 will be available on both x86/64 and ARM devices. Windows 8 is the official product name for x86/64, and for ARM its Windows RT. So, Windows is reimagined to two main editions as Windows 8 and Windows RT. We have Windows 8 Pro also.
For x86/64 Windows is available as Windows 8 and Windows 8 Pro, while Windows 8 is standard edition (not basic) and Windows 8 Pro is for business/technical professionals. You can check more differences between these editions over here on Windows team blog.
In future Windows RT may renamed as Windows 8, at present there are lot of differences between x86/64 and ARM editions, mainly backward compatibility. We may see one Windows to rule all, Windows on PC, tablet, Phone, Xbox and more.
All the best Microsoft, we are waiting for Windows 8, specially those iPad killer tablets.