@Jason isn't this yout idea loopt is doing? http://blogs.wsj.com/digits/2011/06/22/app-watch-loopt-tries-a-groupon-in-reverse/
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
@Jason isn't this yout idea loopt is doing? http://blogs.wsj.com/digits/2011/06/22/app-watch-loopt-tries-a-groupon-in-reverse/