Here's a smaller, lighter electric motor, with a novel drive scheme and lighter batteries available, perhaps of interest to those of you with road bikes and very light assistance requirements. Their netsite is appalling (I can't even copy a photo to show you) and the full spec is missing, but it makes interesting reading nonetheless.
http://www.velogical-engineering.com/velogical-velospeeder.enIf it were cheaper, and didn't require non-standard batteries, I might have bought four and fitted them each side of the front and rear wheels for a decent amount of drive in an all-wheel-drive bike, say for riding offroad on grass and loose dirt.
It's another stillborn project, of course, because a bunch of engineers didn't think to bring in a marketer, as the non-standard voltage required by their motor tells us.