According to a recent article in the NEJM, "Malpractice Risk According to Physician Specialty" we're in the middle of the pack as measured by number of malpractice claims (annually, 8% of ER physicians have a malpractice claim), claims with payment (1.6%), and amount of malpractice payments ($75,000 [median], $180,000 [mean]). The specialties sued most often are neurosurgery and thoracic-cardiovascular surgery; and the least are psychiatry and pediatrics.
Source
Jena, A. et al. "Malpractice Risk According to Physician Specialty" NEJM. 18 Aug 2011 (free, no subscription required)