Actually this is an extract of a Wiki page that I have started today:
http://code.google.com/p/libm3/wiki/Shaders. The aim of this Wiki page is to contains all shaders equations that compute the Starcraft 2 models rendering.
I think this is an interesting research not just for the knowledge of Starcraft 2, but for the deferred rendering generally. So if you have knowledge to share, your help is welcome!
Here are the different render steps for the Barracks :
The wireframe isn't the more interesting, but it's important to view it.
full bright diffuse only
It seems to be the exact diffuse texture.
diffuse lighting only
I think this effect is computed from the emissive texture. It's not exactly the same because, for example, the texture doesn't contain the halo information.
it's normals of the vertices. remember that, in Starcraft 2, Z (blue color) is the up vector
normal map only
It's the normal texture.
It's beautifull... but I have no idea what it is...
specular lighting only
doesn't really look like the specular texture...
Final combination of all effects!
If you are interested into this research, you will find more informations here
Have a nice day (or night) !