What is the best way to take a webprogram and make it into a mobile app without having to start from scratch? I've heard about using Adobe Air? What are the benefits and drawbacks of this and what else do you recommend?

My program uses Google maps api. To give you an idea of it, it has similar functionality to Groupon's map: http _ www _ groupon _ com/now. Whats the easiest way to take something like http _ www _ groupon _ com/now and make it an app?