I just heard Peter Greenberg talking about this on CBS. He made it seem like agents were trolling for people who have too much carry on baggage and offered to valet it so that the boarding process is more efficient. The idea is to put the bags over the passenger's seat.
Talk about rewarding bad behavior....what happens when a number of people start taking
on two carry ons, knowing they might be helped. How will the rules followers feel when they get to their seats and find the OH bins filled?

In absence of any evidence to the contrary, I hate this. Flying LGA/ATL tomorrow, so I might have two cracks at seeing this.