I'll throw in 2 baht on this very interesting discussion.
I read a bit from Ajahn Thanissaro's treatise on Buddha Nature: This is why the Buddha said that the mind is luminous, stained with defilements that come and go. Taken out of context, this statement might be construed as implying that the mind is inherently awakened. But in context the Buddha is simply saying that the mind, once stained, is not permanently stained. When the conditions for the stains are gone, the mind becomes luminous again. But this luminosity is not an awakened nature.
This status of luminosity suggests to me that, rather than the mind having Buddha "nature," the mind has Buddha potential. Inherent potential. This idea of luminosity suggests potential energy that does not convert into momentum until it is released. The analogy of that is the kyudo archer, who draws the bow (potential energy) and by virtue of the meditation, the moment arrives on its own accord and the arrow is released.
By the way, I failed physics in college. I have practiced kyudo, though.
The above is what you get for 2 baht.