Many years ago, you could judge an organization by the professionalism of their sales force and the quality of their marketing documents ("Hey nice suit, and gosh that's an impressive brochure!")
Now, nobody wants a sales call and nobody reads brochures. Buyers do their research, gather recommendations from people they trust, check out the organization online and make their purchase decisions before they ever pick up the phone. (This is true for both candidates and employers).
Google is the new business card ... and brochure ... and sales force. Your reputation is now your digital reputation--whatever shows on the first page or two of the search results.
An engaging website with great content is expected by everyone. Authentic, online testimonials are expected by most people. A healthy social media community is important to the social media savvy people. A quick Google search should reveal a blog or a book or an interview that reflects well upon you and conveys how you view the world. Oh, and it doesn't hurt to have something else impressive pop up on page one of the Google results, perhaps an an award or something...
Why are so many executive search firms still operating with a bare-bones online presence? I can tell you from experience that it takes years to develop enough content to support a robust online community, and whoever gets started earliest often gathers the most attention.
In every sector of the economy, almost every organization is working diligently to make their marketing and communications efforts more social media friendly.
But when you look around, most executive search firms are still woefully behind the curve. Firms that are not gaining experience in social media and firms that have not invested in becoming "digitially approachable" will find themselves falling further and further behind.