this is a really cool new concept for a mobile phone company, and a trend i see many other retailers adopting in the near future.
giff gaff is based in the uk and call themselves the "first people powered mobile network." basically you order a sim card from giff gaff, pop in into any unlocked mobile phone and away you go. you get rewards for recruiting new members to the network, and for participating in giff gaff's marketing promotions... ultimately building up a new community that i imagine giff gaff are hoping will have the same following as other social media sites like facebook and twitter in the future.
whether this takes off is basically just a matter of time, and how many people they can get involved in the site. it would need a lot of promotion and encouraging the right kind of people to join the network in the beginning. people who are heavily involved in social media and the blogging world would be a good primary target to spread the word. here is an overview of the process.
The forums have a good number of posts so hopefully it will be a good concept. i could see other online retailers taking up this, asos immediately springs to mind as they have a good community following... i love the idea of getting you online followers to do your promotional work, let the people who love you spread the word.