Cross platform location aware Mobile Application and Website

I have built a Windows Phone 7 Prototype to test out an idea I had & would like to extend the application to Android, iPhone, iPad and eventually to Blackberry as well. The application is very simple- allowing users to find parks either by using their current location, searching for a specifica area, or searching for a specific facility (such as play equipment, tiolets etc). At this stage, there are 3 main screens: Search screen Results screen Detail screen Eventually I would like to extend this to allow users to rate, comment on & recommend the parks. I would also like to have the site viewable without logging in, but to have the ability to integrate with Facebook for account/user management and so that users can share their feedback & recomendations with friends. There will also be a need for an Web based site to allow users to access the same information online. The back end for tracking the data, users and ratings will be stored in the cloud - I currently use Azure Table storage to host the sample data I have used for my prototype. More details can be provided if needed and the existing prototype code can be provided.