Microsoft has confirmed that windows 8 work is in progress. 
Windows 7’s next brother is going to be released some where around 2012. But no information regarding windows 8 GUI or features has been out at the time of writing this.
Windows fans has started dreaming of new ideas and features for Windows 8. Here is a pack made by one of the windows fans to Transform Windows 7 To Windows 8.
The pack comes with new boot screen, login screen, new redesigned wallpapers and a redesigned taskbar. The developer name this as Windows 8 Professional Transformation Pack.
Though these new changes in this pack are imaginary, at least you can give a new look to your desktop.
Also you can use tune up utilities to apply the new visual styles, login screens and boot screens in windows vista and windows 7.