Unity 3 Particle question

Hello, I am using Unity 3 beta, and I am trying to understand how to “blow out” the intensity of particles, similar to the picture below:

Does anybody know how they are doing this in the demo?
Generally, in an engine that supports HDR, I have simply multiplied the texture’s R/G/B channels in a special particle shader, however Unity seems to clamp these values at 1. I feel like I’m missing something incredibly obvious, as they seem to be doing the effect I would like in the above photo, and not a simple additive effect. Thanks!

It looks like a simple additive effect to me.

Some of the particle shader have double intensity (so you set them to ‘half’ brightness for normal, and ‘full’ brightness to blow out a bit) but even without that once you stack a few additive particles on top of each other you’ll see the type of glow pictured there.