He argues that it's your resume that needs to include key words from job postings since it's those that get placed into recruitment databases and, as a result, searched. Cover letters, meanwhile, don't even make it to the database so there's no point in putting keywords (or, according to Rosenberg, any effort at all) into those. In other words, resume search engine optimisation (SEO) for job description keywords is crucial. In fact, that is precisely what will get you through to the interview stage.
He has a point and I wonder how true this is for Australian companies and recruiters. It sure sounds plausible enough. That said, this is not going to stop me from writing cover letters. Doing at bit of SEO work on my resume may get me past the first cut but I'm pretty sure my cover letter will have a bigger role to play in subsequent stages. The resume SEO tip is really useful, though.