I have two pitbulls, Ginger and Tex. I worked in pit bull rescue for a number of years, and most people really don't know the truth about these wonderful dogs. Please check out our rescue site to learn more about the breed: Pit Bull Rescue Central
Like the other posters said, *any* breed has the potential to be dangerous. Although I know that my dogs would never intentionally hurt a child, they are large dogs (50-60 pounds) and jumping up can hurt! I would never leave a child alone with any dog, ever, period. But, I wouldn't worry more just because the dog is a pitbull.
Here is a picture of my sister's pitbull, Molly. Pumpkin Girl
Edited to add: that link doesn't work unless you cut and paste the URL into your browser.
So try this: http://www.french-roast.com/images/trickortreat.jpg
p.s. my girl Ginger is so loving. She often bathes with me (but only if there are bubbles -- she insists on that!). And she was my daily support when my morning sickness was really bad. She literally placed her body under my arms to walk me around the house all day!