Last year i did some study on pixelshaders and how i could turn point data and normals into light, reflections, refractions and shadows.
As a part of that study i created this simple Translucency shader for Nuke.
Nuke Scanline Translucency/SSS Gizmo from Hagbarth on Vimeo.
Using a projection node with the backface option turned on i can return the backside of the model. Substracting it from the front you get the thikness of the object. Slightly blurring the result and grading it gives the illution of Translucency.