From the article:
"The Oltre XR2 has an internal battery for Campagnolo EPS electronic shifting. DeRosa have already produced a bike with the EPS battery hidden inside the frame, but this is totally new design - Campagnolo's answer to Shimano's internal battery option. It's a long cylindrical design that fits into the bottom of the seat tube just above the bottom bracket. A cable comes around the bottom bracket - inside the BB shell - and you get a port in the frame where you can recharge. You can remove the battery from the frame if you really need to, but it's designed to stay in there. Oh, and It's 60-80g lighter than an external battery.
Neat, huh? It certainly makes a whole lot of sense; there's plenty of empty space inside a bike frame doing very little. You might as well make it earn its keep."
Trek Fuel EX9