I am applying to an MS program in CS. I have not published any technical papers, mainly because I had little opportunity to do research and I did not want to write a paper just for the sake of it. Will I be rejected for this reason? Also, do I stand a less chance of admission than my friend who has written an average technical paper (dumb topic IMHO)?
There is no way to predict whether you will be accepted or rejected from any graduate program. Graduate admission is a random process. You have some influence on the expected outcome, but the variance is set differently by each department, and you only get one trial per department per year.
That said, as far as I know, there are no CS MS programs that restrict admission to applicants with prior publications. There are PhD programs where most students in some research areas had published (or at least publishable) results as undergraduates—algorithms at Princeton, for example. But even in those programs, and in those research areas, publication is not an actual requirement for admission.
It is a little bit of a simplification (and an avoidance of your actual question), but in general the only reason applicants get rejected from a graduate program is lack of space and funding. Being rejected generally doesn't say anything about you or your application. All you can take away from a rejection is that the department ran out of space and funding before they got to your excellent application.