Here's a interesting idea on the interpretation of retrograde planets from Jeffrey Wolf Green (maybe some of you have already read this).
Jeff's take on retrogradation is that in the "normal" course of events all the planets are moving in a forward motion on their ecliptic path. When they appear to move backwards - it's like they are moving against the flow.
Therefore the concept can be attached to the idea that should a planet be direct in your birth chart you will be expressing the energies of that planet in unison with the general flow of expression but should a planet be retrograde in your chart then it is more likely that you are expressing the energy in your own way - against the general flow.

Any thoughts on this????