GitHub topics was introduced January 31st and allows a quick way for maintainers to tag their repository for others to find.
In the repository list the descriptions for an repository become much more important. As more projects add topics a small change can be made to stand out like prepending an emoji.
Any emoji's can be used along with arrows to bring attention to the applications.
Hopefully this doesn't get abused, but for now it's a nice way to stand out a little more.