The most commonly sold form of pancetta in supermarkets are cubetti, which means as Loprraine said, cubed. They are italian style bacon, there are two variations, affumicata (smoked) and dolce (mild).
Pancetta can also mean a simple cut of pork not treated or salted like bacon, a fatty streaky part from midsection, from which, of course, the italian style bacon of the same name is produced.