http://data.london.gov.uk/datastore/package/tfl-cycle-hire-locations
http://www.tfl.gov.uk/tfl/syndication/feeds/cycle-hire/livecyclehireupdates.xml (live feed)
http://borisapi.heroku.com/ (not as up to date, but does the conversion for you)
http://bike-stats.co.uk/ (another 3rd party provider)