I heard about this story on NPR today and followed up on the source's web site, which is the Journal of the American Medical Association. To summarize very briefly, many hospitals now use a system called the "Computerized Physician Order Entry System" (CPOE) for patient prescription input. After a study they found the system's workflows and UI were so poorly designed that at best they're inefficient, and at worst they can cause serious problems. In one of the interviews on NPR today the gentleman being interviewed said that if, for example, you wanted to take a patient from an 8-per-day dosage of something down to 4-per-day, you had to enter the new dosage first, and then cancel the old dosage. If you just enter the new dosage and something happens or you get pulled away, then suddenly that patient's getting a 12-per-day dosage. Yikes!
I just thought it was interesting because while we all of course strive to build systems that are user-friendly on the front-end and robust on the backend, in cases like this a poorly designed system can cause serious problems. Even though the systems many of us develop might not be this mission-critical, it's a good case study in what not to do when we build applications.