He's finished his first project, the "Helpful posts" feature, based on the discussion in Time to revisit the "Like" button?:
Mark post as helpful, click the thumbs up. If you've accidentally marked a post as helpful, click it again.
The button is only shown for others' posts, i.e., you can't vote for your own post.

See the banner below on this post. Initially it shows 1 star and "Helpful". With enough votes, it shows 2, 3, or 4 stars for "Quite Helpful", "Very Helpful", and "Extremely Helpful".
