See the below link for he MIT OCW "Introduction to Computer Science and Programming" course syllabus. Note that they are going over topics like Hashing, Graphs, Monte Carlo Simulations, and Dynamic Programming in an "introductory" course. No mention of basic topics like data types, associativity/precedence, or even assignment statements--in short, topics you would expect to devote a whole class to at the Freshment CS level. I can't imagine covering this material in a computer science class where the students has less than one year of programming under their belt. Seems like its meant for someone already well versed in the computer science field.
MIT OCW - Intro to Computer Science & Programming
You are exactly right. I read somewhere most of the students in the MITx classes are working professionals. The attrition rate is extremely high as well: 120,000 enrolled and 10,000 left @ mid-term exam.