The contract is only for ticket offices, escalators and platforms because it would have required major construction work to have added connectivity to the network's tunnels. But if you are on the Tube in an area within the 80 stations covered, there may be enough range to pick up a connection on a train itself.
120 stations will be fitted out by the end of the year.
After the period of free access, Virgin Media's broadband & mobile customers will get continued access as part of their subscriptions. Other non-paying users will be limited to a site showing online travel information.
Boris Johnson proudly declared that "Millions of passengers will now be able to connect to their work, friends or access the latest news and travel information whilst on the move,"
"This is a fabulous new and free resource which will be in place from this summer when London is being showcased on a global stage and playing host to millions."
Neil Berkett, chief executive of Virgin Media was also keen to point out this would be happening in time for the Olympics and said: "With the eyes of the world on London this summer, we'll be showing off our capital as a leading connected city on the global stage".
London Underground staff will be responsible for fitting the equipment, but TfL stressed that the cost would be covered by the commercial contract. Virgin Media is building the wi-fi network from a total capital expenditure budget of about £640m for 2012.