Meta keywords have historically been a seo best practice that helped sites get ranked depending on keyword research used. Currently, we have 1 legal vertical site and the medical sites which get traffic from Yahoo. It is important on these sites that we maintain optimal keyword research to rank well (aim for #1) in yahoo search results.
Impact: Meta keywords is a good seo best practice that we should be following regardless of whether we rank well in any particular search engine or not.
