Considered to be the finest of the Ethiopian coffees. Others include Harrar, Jimma, and Abyssinian.
As of this writing, Yirgacheffe can be bought green for about $4.00/lb, which is roughly the price you will pay for Sumatran, and about a fifth the price of Jamaican Blue Mountain.
Body is medium, taste is sweet and spicy, with a distinctive floral bouquet. After having spent some more time drinking Yirgacheffe, I have to add the description, "not subtle of flavor". If you are trying to introduce a friend to the joys of coffee, I don't think a double-ristretto made from Yirgacheffe will do so gently. I would have said that there is no other bean that tastes like this one, except that I have recently tried some Kenyan, and realized that it tasted quite similar, just slightly toned down.
Yirgacheffe is wet-processed
I've been told that if you are home-roasting, you should stop just when you start to hear the second crack.
Yirgacheffe is a town in the Sidamo region, a high plateau north of Harar.
I should also mention that Ethiopia is where the Arabica bean originated, and has subsequently been spread throughout the world. The other type of coffee bean is Robusta, which is not held in as high regard, but is used in even the best espresso blends to add flavor.