Have a look at this:
How transatlantic traffic looks from space ? video - BT
It's a nice animation of all the traffic across the Atlantic from a busy period during August.
A few questions: what are the rules for separation of aircraft when crossing the Atlantic? It seems from the animation that the tracks are separated laterally by quite some distance. Laterally, do the aircraft have to comply with RNP-10? Presumably the RVSM height separation rules apply? Lastly, do the tracks get moved (North, South, higher or lower) when the Jetstream changes position?
Would be useful to hear from pilots who fly these routes and/or air traffic controllers who manage them. Thanks for your help.