I’m not an SQL expert, but I would think you might have to JOIN twice to pick two distinct rows out of wp_postmeta
:
$featuredquery = "
SELECT wposts.*
FROM $wpdb->posts wposts
JOIN $wpdb->postmeta article_level ON
( wposts.ID = article_level.post_id AND
article_level.meta_key = 'article_level' )
JOIN $wpdb->postmeta article_genre ON
( wposts.ID = article_genre.post_id AND
article_genre.meta_key = 'article_genre' )
WHERE article_level.meta_value="Hovedsak"
AND article_genre.meta_value="X6.no (Spill og underholdning)"
AND wposts.post_status="publish"
AND wposts.post_type="post"
AND wposts.post_date < NOW()
ORDER BY wposts.post_date DESC
LIMIT 0 , 4
";