I've been using group assignments in a course, and can't find a way to tell which student in a group submitted for the group.
I've looked at the entries in the SpeedGrader - I see the time of the submission, but no indication of which group member made the submission. This is true with both grading options - all group members getting the same grade and grading group members individually.
I've also look for this info in the gradebook. Mousing over each students row under the assignment makes it look like they submitted. Also, clicking the little discussion icon to open a window with details, still makes it look like all students made a submission.
I've realized that this could be important. One part of the group assignment is weekly status reports which are supposed to include updates from all students in the group. In grading, any student who doesn't have an update in the status report gets a 0. But when there are questions from the student about this, I can't tell which student submitted the status report to see if they just overlooked an update from one group member.