I found this on a Japanese site:
bigger pics:
http://ysroad-shibuya.com/assets_c/2...407-11489.html
http://ysroad-shinjuku-crossbikekan....s/P1040894.JPG
Shimano Alfine CT-S500 chain tensioner, Tiagra FD with a 48/36 crank. It's basically what I had in mind without the IGH. Still looks cleaner than a cassette and RD.