Press Release sites are a great marketing tool for job boards. There are two pay sites worth using as well as a number of free alternatives. The free sites below are great for link building but they wont bring much traffic.
eReleases.com (pay)
PRweb.com (pay)
PR.com (free)
PRlog.com (free)
i-Newswire (free)
Job Boarders (pr section of forum) (free)
Secrets of the Job Hunt (forum) (free)
Recruitingblogs.com (pr section of forum) (free)
ERE community (free) (create an account and publish as a blog post) (example)
Use these sites to announce the launch of your job board and inform potential seekers and employers about the industry you serve.
Here are some examples from the employment category on PRweb