BP Reactions adds emoticon reactions to the activity stream in BuddyPress, but the more interesting development is the discussion around merging it with BP to replace the favorites functionality, as there is a five year old issue with how favorite information is stored in the database.
I’ve been building a BuddyPress site, and BP Reactions is a welcome addition, and I wouldn’t mind having it replace the favorite functionality, though I may end up using the Favorites plugin instead, since I am using it for other content in my project.