That question has arisen in connection with the creation of on-line repositories for job ads. Rebecca Kukla (Georgetown) forwards the following useful information, from the US Dept. of Labor:
Is the employer permitted to use an electronic or web-based national professional journal instead of a print journal when conducting recruitment under 20 CFR 656.18, Optional special recruitment and documentation procedures for college and university teachers?
Yes, an employer may use an electronic or web-based national professional journal to satisfy the provision found at 20 CFR 656.18(b)(3), which requires use of a national professional journal for advertisements for college or university teachers. The electronic or web-based journal's job listings must be viewable to the public without payment of subscription and/or membership charges. The advertisement for the job opportunity for which certification is sought must be posted for at least 30 calendar days on the journal's website. Documentation of the placement of an advertisement in an electronic or web-based national professional journal must include evidence of the start and end dates of the advertisement placement and the text of the advertisement.
http://www.foreignlaborcert.doleta.gov/faqsanswers.cfm#cutrec6
I'm going to open this for comments from anyone with additional information, and I will ask some law colleagues who work in this area to weigh in.