I need to find the latest post for each author and then group the results so I only a single latest post for each author.
SELECT wp_posts.* FROM wp_posts
HERE a simple answer from http://www.cafewebmaster.com/mysql-order-sort-group
SELECT * FROM ( select * from `my_table` order by timestamp desc ) as my_table_tmp GROUP BY catid ORDER BY nid desc
it worked wonders for me