Is Yahoo still important to my site - if I'm purely B2B?
Enjoy this blast from the past: back when the Yahoo! Directory was still a power player in the SEO game, this was our advice. Now that it’s no longer functional, we can direct your SEO efforts elsewhere—contact us to get started.
Absolutely. A link to your site from the Yahoo! directory gives search engine spiders another path to your site and improves your site’s “popularity” (the number and quality of links to your site). Google and Bing factor in popularity when giving your site its ranking.
So, getting listed on the Yahoo! directory will help you to rank better in searches performed on most of the other search engines.