Work has begun to build the new docking stations which will extend the scheme south and west. They look set to become operational in the autumn.
Details of the docks being planned in Wandsworth are available here.
Other boroughs included in the extension are Hammersmith and Fulham, Lambeth, and Kensington and Chelsea. Plus there will be a few new docks in the existing zones.
Some useful background is provided in this TfL paper.