This is examples of smoke made in blender.
http://akhil.nightmail.ru/smoke_softbody.mkv
http://akhil.nightmail.ru/firesmoke_softbody.mkv
both are 100 frames matroska encoded with x264 and ~51Kb of file size.
And the blend file http://akhil.nightmail.ru/smoke_softbody.blend.bz2
Press the bake button on softbody dynamic panel after opening and after baking render any frame.
Notice the stress button on the texture mapping panel of smoke box.
Hope in some day blender will have voxel smoke simulator.