Bikes Direct has a Di2 equipped bike and while $3700 is way out of my price range it didn't seem to ridiculous for the people looking at a really nice bike. I don't knwo how that one compares in additional cost to their other similar DA carbon framed equipped bikes.

http://www.bikesdirect.com/products/...eam_di2_xi.htm

It seems like in the future this could be a relatively straightforward technology and the cost wouldn't be too much greater. Its not like I want to buy it or anything, but its been said already there are some great applications for this system and I think there are some everyday joe's out there that would possibly enjoy this system too once the cost is lowered.