This is an exciting update! I'll be very short because this is something VERY technical and honestly, that's not my realm ;P Still, I found it worth sharing because Cycles just got a 10x speed up in render times!
10 times faster is a lot, isn't it? Well, this is not for every render. Let me explain: some situations are especially complex to render, overall when these complexities exist together in the same scene (many reflections, advanced shaders, hair, motion blur, depth of field...). In those cases render times were prohibitively high, making such complex scenes impossible to render in a reasonable time (or at a reasonable price, if you decided to use a render farm).
And this is precisely where improvements have been made. New systems have been implemented to improve memory usage and generally optimize the render process, which will help render such complex scenes (specifically those ones involving motion blur) A LOT faster.