Apparently Facebook wants to remind users that Facebook Groups is for creating a circle of people who are involved on the same project or working together for some purpose not so much for advertising or promotion. The slight change replaces the single profile picture with a slide featuring all who are included in the project.
All Facebook, a resource for Facebook information has been promoting the use of fan pages for advertising rather than clogging up the Facebook Group profiles.
Hector Kolonas, a writer for All Facebook says:
"We have seen a growing amount of resentment building against brands who use groups, due to the annoying notifications they produce and the opt-out structure of joining them."
So this is a good tip, especially if you're someone presently using Facebook Groups for promotion or advertising. Thanks Hector!