Custom WordPress SQL Query 4 posts per custom taxonomy

This is possible, but there’s not a “neat” way to do it. There’s a great write-up here:

Display the Most Recent Post in Each Category

but as the author points out, it’s a separate query to get the most recent posts for each term. To his great credit, he does deal with caching them, which will help tremendously with the load this would place on your database / server.