WiFi has become something of a buzz word these days, seems like it's everywhere from coffee shops to libraries to hotels. It increasingly feels like you can get online pretty much anywhere, and with the advent of city-wide wireless network coverage, for the inhabitants of numerous cities across the globe this is actually becoming the case. The world it seems is rapidly being turned into one giant WiFi hotspot.

The WiFi revolution is about to hit London in the form of a vast 22km network. If you're prepared to live with relatively sluggish download speeds of 256kbps the service, which will initially stretch along the Thames from Millbank to Greenwich, will be free, if you need a faster connection, ?2.95 an hour or ?9.95 a month will buy you 500kbps.

According to MeshHopper the company behind the venture which is being branded as "online-4-free", the one condition for those using the free service is that they'll be required to view 15 to 30 second ads every 15 minutes, those paying for the faster service won't have to.

This venture is being heralded as important not just for its huge scale but because it's free. It follows on the back of a city-wide service launched in Norwich last year and anticipates a free network due to be launched in Manchester in August.

According to Dan Toomey, chief executive of Free-hotspot who joined forces with MeshHopper in the project "This really marks the arrival of free WiFi in Greater London. Millions of Londoners, as well as commuters, visitors and tourists can now expect to find free Wi-Fi as they work or play along the Thames." Of course, whilst free to those willing to tolerate less than blistering speeds and the occasional interruption of ads, this is a undeniably a commercial venture. In this respect it will be competing with The Cloud's offering which will cost ?11.99 a month after an initial free month but may well give surfers faster speeds.

When Norwich launched its pioneering council run city-wide wireless network last year there was a degree of controversy with Broadband providers regarding it as potentially damaging competition; for this reason speeds had to be capped at 256kbps and sessions limited to an hour only.