I had this idea and was almost ready to develop the application when i found this patent, US 20080140650, which covers most of things I have thought of. Has this idea been implemented or is it just stuck as an idea as of now.
Your cited patent application has been granted as patent # US 8,108,414 B2. Take a look at the set of features in claim 1, for example, of the granted patent, as they are different from the application's.
Unless challenged and found to be invalid, the '414 patent is presumably valid. You should talk to a patent attorney to determine whether there is a claim infringement issue related to your application idea.