I'll throw my useless observation in here... the only thing I use translucence for is for illuminated signs that use an image map or for computer monitors. Plug the image map there rather than diffuse, ambient set to 0, translucence set to 1, get the image lit like an LCD monitor.

On the very rare occasions I've tried computer monitorsor TV screens in my renders I've used ambient. Any specific reason you use translucence instead? Back to the leaves - I tried the back-lit front-viewed and front-lit back-viewed experiment on the ivy I'm using with its default shader, and with the translucence connected as bagginsbill noted. Lighting was just an infinite (with ray-traced shadows - the translucence/shadows didn't seem to work with depth-mapped shadows) and IDL:

(bottom right caption should of course be "Back-lit front-viewed with translucence")

And here's the shader with translucence (I noticed as I was posting this that I used 1.0 for diffuse/translucence strength, whereas bagginsbill used 0.8.And the diffuse colour on the shader I used wasn't quite white):

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The 3Dcheapskate (also available in DAZ and HiveWire3D flavours) occasionally posts sensible stuff. Usually by accident.
And it usually uses Poser 11, with units set to inches. Except when it's using Poser 6 or PP2014, or when its units are set to PNU.