An interesting tidbit from the recent Yahoo! HotJob Survey:
The survey found that only 9% of respondents have used social networking sites to find a job, and only 1% thinks it’s the most effective way to find a job. Moreover, 38% of job seekers feel that using social networks doesn't improve their chances of finding a job. And only 23% of hiring managers and recruiters are using social networks to promote their job openings.
For all this white-hot hype about the "Social Web", there is actually very little evidence that it is having an impact where it matters.