AgeLesS - yes that’s correct, except the particles are duplicated off a mesh similar to the ground plane.
DYeater - yes the technique is similar to beast with textures mapped to planes.
Cativo - yes i used a targa with an alpha map.
Raseri - I’ve been playing alot with static particles too, and they have the potential to be much more powerful, I agree. However, until they (halo textures) get moved in the render pipeline, they can’t be involved with ray tracing at all: no shadows (not even buffered), no reflections, no ambient occlusion. Basically they usually end up looking like they don’t fit in the scene. I am playing with the idea of mixing this duplivert technique with normal static particles because they’re powerful enough to create even simple plants with branching, etc.
FiXXXer - Unfortunately they are rather limited for animation. The best way I can think is perhaps an animated texture, or perhaps vertex keys on the plane, but either way every plane will do the same thing, which may look unnatural, but I haven’t tried it. As far as the particle duplicator feature goes…there’s a full description here: http://www.blender3d.org/cms/Particle_duplicators.443.0.html