I've had a blog post loitering in the back of my mind about the relative costs of digital vs film - my take on it was from the post-processing phase, so it was really interesting to read the article Is Digital Cheaper Than Film? yesterday, considering the issue from a total cost of ownership perspective.  Here's where I'd got to (it's probably worth mentioning that I do this for fun and not to make money from):

"When I'm shooting film, I generally take one or two photographs of a scene. With digital I'll take several, sometimes chimping to see what I'm capturing which usually results in me taking a few more with different exposure settings.

With film I think first, take photograph second. With digital I think a little, chimp a little, think again. 

This means I end up with more digital based assets to tag, to review, to compare and find the best, to process, and to store. All of which takes time, and it is the time element that I rarely see factored in to the digital is cheaper than film calculation."