Unity Photos lens is just like Music and Videos lens of Ubuntu, the only difference is that it displays photos. Whats more, it can pull photos from several online services like Picasa, Flickr and Facebook and display them right in your dash.
With an update, the photos lenses have landed up in Ubuntu Quantal, thus increasing number of lenses to five. The photos lens use Gnome online accounts as backend, so if you add your Google account, you will be able to access Picasa photos, with Facebook account, your Facebook albums etc.
The developers are currently working on the code that will allow you to upload photos right from your desktop.