When I was in university, I do not recall them really teaching us "hello world", our first assignment was to do with graphics already (this was a first year intro CS course).
Anyway, the way we had it was we had a few labs that we had to do to get us familiarized with the environment (how to compile, how to list directories, how to log in and log out). The "hello world" would be perfect for a lab task.
The intro course itself could start teaching OO concepts from the get go. We learned other concepts on my day, but I think this would be the best way to teach an intro to CS course.
Also on a side note, our labs were basically graded as "complete" and "incomplete", and do not count to your final mark because someone who knows programming will think its a waste of time anyway. But beginners would have an opportunity to understand how things work.