Perhaps the light trails are simply a function of shutter speed, that's one of the variables we can control that would result in such effects.
I wonder how feasible pausing, entering Photo Mode, processing then resuming a replay would be. I get the feeling it would be pretty hard - Photo Mode seems to make use of as much processing and memory as it can to get the best result. As has been repeatedly mentioned, instead of having to render a scene in 1/60th of a second (or 1/50th), the PS2 can take far longer, a second, perhaps more. That doesn't mean it's going to be 50-60 times better, but it counts for something. The increased resolution is why things look so much better, particularly on the comparatively higher resolution of computer screens.
What I'm curious about is just how we're getting all these high quality photo mode pics, are they all just screen captures with a video in or is there a transfer system in the works.