MiikaH's second smoke patch changes:

Domain border collision settings.
 - It's now possible to change how smoke collides with domain walls.
   Turning off collisions may be essential when having a horizontal force
   field applied to smoke.

Vorticity slider
 - You can now change smoke vorticity. It defines how much turbulence or rotation
   fluid has. So lowering it gives you very smooth smoke.

Time scale slider
 - This slider allows you to tweak simulation speed / time. If you lower this value
   simulation goes slow motion.

Non-Absolute density on emitter
 - There is a new button on smoke "Flow" settings. Absolute. When enabled, emitter behaves
   just like before: adding smoke exactly with the density given.
   Without it, however, emitter can work as an additive source. For example having 0.1 density can
   still give very dense smoke but smoothly, slowly increasing the previous density.

Smooth High-Res Emitter
 - You may have noticed that using high resolution can lead to strange "blockiness" near emitter.
   Now you can easily get rid of it by enabling "Smooth Emitter" on high resolution settings.
   It makes emitter to create interpolated round shapes instead of cubes.

"Initial Velocity" multiplier
 - When tweaking this value you can adjust how much of the particle velocity is transferred to smoke.
   You can even use negative value to reverse emission direction.

High-Res strength can be set to 0.0
 - As a minor change this can be useful when you need sharper smoke (read high resolution), but
   not the turbulence. For example I found this usefull when making a candle flame.


Get the smoke patch here : http://www.miikahweb.com/other/mhSmoke_SecondPatch.patch
or visit my site for other stuff: http://www.miikahweb.com/