We have covered this topic in past when Windows 7 was released by Microsoft:
Windows 7 comes with new feature "Pinned items" which has replaced the good old Quick launch toolbar from Windows 7. Although you can get the Quick Launch toolbar back in Windows 7 using this tutorial.
Recently our active reader "Uewd" found out an interesting thing. Microsoft has also mentioned in Windows help why did they remove Quick Launch toolbar in Windows 7.
1. Click on Start ORB (Start button) and type "What Happened" in search box.
2. Click on the link present in Search results or simply press Enter.
3. It'll open a Help window which will tell you the reason behind removal of Quick Launch toolbar from Windows 7.
Interesting find by Uewd...