Evolution and the Christian doctrine of Imago Dei

Aside from exegetical issues surrounding the first few chapters of the book of Genesis, there really doesn't seem to be much conflict between the idea that a divine Creator exists and that life as we know it is the product of an evolutionary process.  It doesn't seem so hard to imagine that God set the initial conditions and started the process off, perhaps making a few tweaks and adjustments along the way.

One area that does seem to create some tension, at least in my mind, is the doctrine of Imago Dei.  This Christian doctrine roughly holds that humankind is made in the image of God.  What does this mean?  Since Christian orthodoxy holds that God is not a physical entity, being made in the image of God can't be interpreted as being made in the physical image of God.  If that's the case, then by "image" we must mean some kind of emotional, intellectual, spiritual, or volitional faculty (or perhaps all of the above).

If it is indeed the case that man is made in the image of God, then this question is put to those (including me) who believe in the truth of evolutionary theory.  According to evolutionary theory, mankind is a descendant of a number of lesser developed species.  If this is so, then at what point was the image of God imparted in man?  Humankind is a descendant of early one celled organisms.  Surely these organisms did not have the image of God.  The same could be said of other species that are part of humankind's evolutionary lineage.  One might point out that the image of God was imparted when the species Homo Erectus evolved to the species Homo Sapiens.  However, this transition was gradual.  Can we point to some exact event where the image of God was imparted?  If so, where and why that event?

For those who interpret the first few chapters of Genesis literally, the answer to this question is simple.  The image of God was imparted on the sixth day of creation when God created humankind from dirt and breathed the breath of life into them (or at least him).  Here there is a specific event that can be pointed to as the event where the image of God was imparted.  Of course, this answer comes at the cost of a highly implausible account of the Earth's origins.

So suppose that you identify as a Christian whose beliefs are more or less orthodox.  Suppose also that you are convinced by the theory of evolution as accurately describing the history of life on Earth.  How do you resolve this apparent tension between science and religion?