What The Heck Are 3D Chips Anyway?

If you've heard about 3D chips and wondered what all the fuss about them is, let's see what Wikipedia has to say for starters:

In electronics, a three-dimensional integrated circuit (3D IC, 3D-IC, or 3-D IC) is a chip with two or more layers of active electronic components, integrated both vertically and horizontally into a single circuit. The semiconductor industry is hotly pursuing this promising technology in many different forms, but it is not yet widely used; consequently, the definition is still somewhat fluid.

Here's the link to Wikipedia for more on this subject.