Deli meats like salami are best avoided because they carry a higher risk of listeria and other dangerous bacteria (same goes for other unpasteurized products as noted above---soft cheeses, anything containing raw egg like cookie or cake batter or mayonnaise, etc.) The chances of something actually happening are pretty low but as expectant mothers I know most of us would choose to err on the side of caution.
Another note about salami----some types of salami have been treated with nitrates as a preservative. Nitrates are also used in smoked meats, bacon, and most hot dogs, kosher/beef or pork varieties. Nitrates are proven carcinogens and it's best to avoid these just for the sake of not exposing the fetus to them. So that's another reason I would have to refrain from any more salami during pregnancy...