CityWatch is made by Zannel, a media microblogging service that is similar with Loopt and Whrrl. And since its initial launch back in the late 2007, Zannel finally released CityWatch for iPhone/iPod Touch (software v2.0 or above required).
The free app allows you to see and interact with what's going on in your surrounding. CityWatch access your account at Zannel, takes the items you've posted and then shows them on the iPhone screen while overlaying it onto a map using its geo tag. The app also support authorization from other social networks, like Twitter & Flickr.
Josh Lowensohn from Webware has tried the app, and here's his take on it:
"What's neat in Zannel's case is that this activity becomes exploratory and interactive, as you're able to both post and browse through new content in your city or anywhere else in the world. You can also reply to comments in threaded form, just like you can by using the social network on your computer. Eventually users will also be able to sort through all Zannel's content not just by location, but by topic across the entire network."
Josh also found an annoying ability of this CityWatch app; "it relies a little bit too much on Safari when it comes to making changes in its settings menu. If you want to authorize Twitter or Flickr, you're kicked off the application and into the browser."