When I was job searching right out of university, one of the reasons I stopped looking at big job boards is that they tended to be filled with jobs from recruiting agencies that wouldn't name the client and would instead show themselves as the employer. I hated that because the type of company was so important to me and what recruiting agency wasn't going to say their client had a position at a "dynamic successful company" where you'd work on "cutting edge technology". They say potential employers spend 30 seconds looking at resumes; I always joked that potential employees spend even less time looking at job postings. If I couldn't figure out what kind of company it was, why would I waste time writing a cover letter?

Although, now that I'm on the other side, I can see why I don't like traditional job listings either. If I post a developer job (at this startup) on something too public I get spammed with mediocre applicants. It takes a long time to sort through them all, and that's time I could be programming.

I do believe this is a problem in need of a decent solution, but I agree that it spreading virally doesn't really differentiate it from traditional means.