The app, named OpenSpot, is very straightforward. If you are looking for parking, simply pull up the app to see a map of nearby openings. Right now, since the application is brand new, there's not likely to be much to find, but eventually over time as more people use the app, it could prove to be a useful parking tool.
If you are leaving a parking space and feel the urge to generously attempt to share your empty space with fellow Android users, you can place a pin on the map where your spot can be found. The app automatically color codes the pins based on how long they've been active, and removes spots that are older than 20 minutes.
The application also has some game mechanics to motivate people to advertise their open space. Each time you share a space you earn what Google is calling "Karma Points." If there's anything to be learned about location-based apps, it's that earning points, badges and mayorships is a fun way to boost usage.
This is a great solution for busy cities and an obvious evolution of location-based technology. Eventually as technologies like geofencing allow people to check in and out of locations automatically, determining the availability of parking spots could become more easily automated. Better yet, an application could tap into Internet enabled parking meters that have publicly accessible APIs to show open parking spots.
There are a few other applications already on the Android Market and the AppStore that help users share parking information. PrimoSpot helps both Android and iPhone users find nearby public parking locations, and iSpotSwap has the same basic functionality as OpenSpot but for the iPhone. Google's advantage is it can leverage its existing user base to quickly grow the service.