It's easy. Just add this hook for template_redirect action and it will redirect your search queries to nice url:
function wpse8170_search_url_redirect() {
if ( is_search() && !empty( $_GET['s'] ) ) {
wp_redirect( home_url( "/something/" . urlencode( get_query_var( 's' ) ) ) );
exit;
}
}
add_action( 'template_redirect', 'wpse8170_search_url_redirect' );
Add to your .htaccess file:
# search redirect
# this will take anything in the query string, minus any extraneous values, and turn them into a clean working url
RewriteCond %{QUERY_STRING} \\?s=([^&]+) [NC]
RewriteRule ^$ /search/%1/? [NC,R,L]
searchtosomething. – Milo Jun 11 '12 at 14:38