Nuke 8 secretly introduced a undocumented node called ParticleToImage. This node can be used to turn a particle system into raw image data, containing XYZ positions, Scale, and Color data.
I assume the node was introduced to bridge the gab between 3D scenes and the new BlinkScript node.
You can for example apply a particle system to your geometry, choose uniform distribution and you will be able to get all vertices from the geometry. You can also add custom data into the color channels to bridge data like rotation and so.
Anyway, to showcase this node i have made a little relight node that uses the image data to have a Nuke particle system cast light onto a scene. I have used a basic blinn light model with a half-lambert option.
It uses the particle scale to determine the light intensity, and color for the light color.
The node should be available on nukepedia shortly or you can get it directly here
Nuke ParticleLights from Hagbarth on Vimeo.