The Wi-Fi network, serving the West End, offers service at speeds up to 24Mbps.
Users will have to register, but unlike Virgin Media's network on the London Underground, O2's hotspots will remain free after the Olympics are finished. So you might well wonder what the revenue model will be.
O2 aims to support its investment by selling advertising to local businesses, probably adding location features to craft deals based on end user location. There is another difference.
O2 is using the 100 Wi-Fi hotspot deployments as the foundation for a future small cell network that will use O2's 3G network, reinforcing the macrocell network where it is most congested.
As a matter of engineering, that has meant locating the Wi-Fi hotspots in locations where eventual conversion to a GSM small cell network will be compatible with the macrocell network.
According to O2 Wi-Fi managing director Gavin Franks, the carrier is targeting the end of the year for the small cell conversion.