From the article in the NYT:
The mechanism, presumably used in preparing calendars for seasons of planting and harvesting and fixing religious festivals, had at least 30, possibly 37, hand-cut bronze gear-wheels, the researchers reported. An ingenious pin-and-slot device connecting two gear-wheels induced variations in the representation of lunar motions according to the Hipparchos model of the Moon’s elliptical orbit around Earth.
That's just amazing. This would be a huge accomplishment if someone made this today wih the aid of the internet, books from the last two thousand years, computers, and CNC milling machines. Bear in mind, they believe this was made around 150-100 B.C.!
Here's the New York Times article on The Antikythera Mechanism