Actually called boba drinks, but also known as pearl tea, pearl milk tea, or just plain bubble tea.
Originated from Taiwan and spread through-out Asia and finally landing here in the States where yuppies and Asians alike gobble these things up like the new millennium drink.
The pearls themselves are just chewy tapioca and the drinks are usually made with tea, tea mixed in with milk, coffee, espresso, condensed milk, or jelly and fruits of any variety. Some people also mix it with juices and syrups and most notably ice.
Boba itself means humongous in mandarin so essentially a direct translation means that boba drinks are humongous drinks. Why humongous drink? Because the pearls reminded people of humongous breasts and since boba is also slang for big breasts.
Generally sold in various coffee shops of Chinatown centers and supermarkets or just anywhere you see a congregation of Asian stores. Costs anywhere between 2 dollar for some generic cheap variation to 4 dollars for some nifty things such as colored jelly, syrup and tea.
Some great flavors try and add are green tea varieties, taro, strawberries, honeydew.