We've heard Nokia talk about augmented reality being a big differentiator for them in terms of Windows Phone and technology and now we're getting our first glimpse of that endevour.
City Lens seems a lot like LGs Metro Scanner and ScanSearch whereby you hold it up and it shows you things around you. In fact, City Lens even does the "hold it flat to show a map" trick that LG uses too. Still, we bet with Nokia's mapping history and deeper interest in Windows Phone, City Lens will be a much more rewarding experience.
No word on release as it is still in beta, but hopefully we'll see it with the 900's release.
Source: The Nokia Blog