It was with some interest that I watched the "no laptops/coats in overhead bins" rule be STRICTLY enforced on an AA flight a month or two ago. I forget exactly which flight it was... STL to ORD, I think. Due to weather, flights to ORD were heavily delayed/being cancelled so there were a lot of standby pax making the flight full to bursting. (usually they are full-ish, but not jam packed) GA actually did announce 'when you get on the plane, please do not put any laptop bags/coats into the overhead bins as we will not have enough space' and there were numerous announcements made on the plane as well...

Well, as the last zone began boarding, lo and behold, there became no more overhead bin space because of coats/laptop cases/random small articles put into overhead bins. Cue taking-no-crap gate agent cruising on to plane and manually removing all coats/purses/laptop bags and chastising their owners. Long story short, it took about 15 minutes, but everyone learned their lesson on that flight and nobody had to gate-check anything. It was an impressive display. I saw a number of pax hand him an AApplause note.