Intel is putting on quite a dog-and-pony show, announcing what it's calling "the world's first 3-D transistors in mass production." Apparently, the development will allow for the continuing applicability of Moore's Law, which states that advancements in technology will keep the number of transistors that can be placed on a single chip doubling every two years.
The New York Times explains what this is all about. Here's a graphic, but you'll have to use up another one of your allotment of free Times clicks if you're a non-subscriber.
All Things Digital also has a go at it, and says this about the significance of the development:
It’s the sort of thing that gets people who know chips kind of excited and leaves others kind of cold. But in fact, everyone should be kind of excited about this.
- Moore's Law (Wikipedia)