meet-your-city.com

The fact that you are creating an advert for Nokia is great, not only the consumers will connect with the off-line posters but the chance of your photos making it in the real world is appealing. The site let you do your upload without asking for registration beforehand, this always help people to try promotion and should be encouraged more. I don't think the tags work as they can hide some part of the photo and are limited. The site could encourage more the use of the lightbox too but overall it's on brand and even if it's only for London, flagship store obliged, it does 'connect people'.
http://www.meet-your-city.com/
p.s: don't forget to meet Hong Kong too by spinning the globe.