In Unreal Engine 3, when you changed material properties to an ‘Unlit - Translucent’ material, the ‘Normal’ master input node was still available for you to plug normal maps into. While they had no effect on the lighting of the material (it’s unlit), it still had an effect on some of the nodes that you plugged into other parts of the material.
One use for this is with Reflection Vectors. You could add a reflection texture to particles for example, and the reflection vector would distort the texture based on based on the normal texture you plugged into the master material normal input. This is a good way to ‘fake’ liquid-like sprites and make them look more three dimensional, and I used it fairly commonly in blood/water decals.
Transluscent Unlit materials pay no respect to the Normal Input in the material master (it’s greyed out now), and therefore this reflection vector trick doesn’t work either. Plugging the normal texture into the new ‘World Normal’ input on the reflection vector node does yield some change in results, but they are quite different from the way UE3 handled it. If necessary, I can upload some example screenshots to show the differences.