Arthur,
I think, but of course don't quote me, that have modified teh software application of their High Resolution Image process, I think Sony call it Pixel Shift, which effectively uses a slightly different part of teh sensor to take and combine several images to get one much higher resolution image,
The m4/3 is a 20 mp sensor, High Res image produces and equivalent 80 mp image, and works wonders for static subjects, it does however produce a similar effect to the ND option on moving, or partly moving scenes, although at a much higher resolution,

Olympus also have a feature called Live Composite, which is mainly used at longer shutter speeds, Star Trails, which basically captures a base image once, and then only records new light on the sensor, so you can have a 30 second base/foreground image, combined in a 3 hour star trail image, in camera

I think they have used/combined both of these technologies for Live ND

It is called Live ND and you can actually see the effect in the screen before you take the image