The webmaster guidelines advise you to prevent your search result pages from being indexed, WordPress doesn’t do that by default (yet), so I’ve written a small noindex-search plugin which takes care of that by adding a meta robots noindex,follow tag to search result pages.
Tags: WordPress Plugins
Yoast.com runs on the Genesis Framework
The Genesis Framework empowers you to quickly and easily build incredible websites with WordPress. Whether you're a novice or advanced developer, Genesis provides you with the secure and search-engine-optimized foundation that takes WordPress to places you never thought it could go.