http://www.bbc.co.uk/news/technology-17373523

Extract...

---quote---
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.

From July 2012 all Tube passengers will initially be able to connect
to the internet for free.

After the Olympic and Paralympic Games it will be a pay-as-you-go service.

Virgin Media's mobile and broadband customers will be offered continued
access as part of their subscriptions. Other non-paying users will be
limited to a site showing online travel information.

The firm said it intended to introduce wi-fi to 80 stations by the
summer, and by up to 120 stations by the end of the year.
---/quote---