You still remember Aero from Windows 7 with that transparent Aero glass taskbar don’t you? You can enable the Aero themes in Windows 8 to get that back.
What is Windows Aero?
Windows Aero is the graphical user interface and the default theme in most editions of Windows Vista and Windows 7. Its name is a backronym for Authentic, Energetic, Reflective and Open. Its distinctive visual style combines the appearance of lightweight, translucent windows with powerful graphic advances. With Aero, you can enjoy visually appealing effects and appearance and also benefit from better access to your programs.
By default this feature remains disabled in Windows 8 developer’s preview. Hope Microsoft will bring back this feature in later versions of windows 8. If you want to enable this feature, follow these instructions carefully.
1. Press Windows and M simultaneously to switch to Desktop mode.
2. Right Click on the Desktop Screen and select Personalize.
3. When the personalization window appear, then Click on the High Contrast White theme to apply it.
4. Once it is done, then Click on Windows Basic or Aero theme theme to apply that.
Now the transparent glass taskbar is enabled. You can check it by moving any window below the taskbar.
Remember, this transparency will be lost after the reboot. You have to redo the steps mentioned above to get back the transparency. This is a bug in windows 8. You have to wait for a fix in the later versions.