I was in a webinar about the the Intelligent Assessment, about online assessment tool. This tool is used for short answer questions. The most interesting component was that it is capable of gathering facts from the students answers to build its knowledge base. However, setting up the question and feedback takes time. Once it is set up marking seems to be much more easier compared to human manual marking.
The interesting evidence was provided about human error and capabilities of this automated system with different rules to mark short answer questions. The system was linked to a LMS and currently it is available with Moodle.
More information can be found in Sally's Blog: http://www.open.ac.uk/blogs/SallyJordan/