It turns your phone into a police scanner, and depending on your region you can tune in to several different scanners in your region.
When you open the application, you can choose your country and your state. Then, pick your county. Depending on where you live, you may have a few options to a whole list of choices. For Columbia, Missouri, I chose Boone County and I have two options - Boone County Fire and EMS and Boone County Sheriff and Columbia Police. (If you choose Los Angeles County in California, you are given over 20 options).
When you select a scanner to listen to, it tells you the KB per second (KBPS) and how many other listeners there are. There are several tabs that provide a lot of information. The first is time, Faves, Chat, Map and More. Under chat, you can sign in with your twitter account and communicate with other listeners. There is also a list of police codes with their definitions, in case you are not an expert on their lingo. The map tab simply geo-locates the scanner and under more there are more explanations for codes. If you buy the paid version of this app (the full version), you can set an alarm, sleep timer, record and playback the feed. The arrow in the top-right corner allows you to add the section to your favorites, share the feed by email, pick a new skin for your phone scanner and instructions in case you need more information.
This application actually turns your phone into a police/rescue/EMS scanner. As you can see, this application could be wildly successful for any newsroom or freelance journalist.