I flew DOH-LAX in J last week. Checked my DSLR camera and laptop in at the gate. Bubble wrap, box and a plastic bag around the box. The boxes aren't big so I ended up having a box each for the DSLR and laptop. You write down your details on carbon paper and keep one of the copies. On arrival in LAX, they took all the electronics to the podium on the right hand side of the terminal and everyone collected their items one by one according to the luggage tag and the piece of paper you filled in; before signing that you had received the electronics back. Apparently you can gate check your hand luggage with electronics inside them and they'll travel alongside the boxes and be returned to you in the same method as above.

Onboard laptops - I have heard that there are 7 laptops per flight, however only 3 routes have so far been loaded with them (LAX not being one of them). I assume the 3 routes would include JFK and IAD.