Following in the footsteps of Yellow Pages Group in Canada, Australia’s Sensis has created and released an API for third party developers. Local-mobile search app Poynt is so far the only application that uses Sensis data.
Commercial uses have a number of requirements. Those presumably include taking Sensis advertisers and providing branded attribution (e.g., powered by Sensis).
In addition to yellow pages and local search, years ago Sensis tried to create a direct search competitor to Google. It was powered by Fast Search & Transfer (now part of Microsoft). Sensis lost that battle and now works more closely with Google.
The API is part of a larger strategy to distribute listings broadly to multiple consumer destinations.
Several of the US directory publishers have developed or are considering APIs; however I don’t believe any have been released yet — or they haven’t made much noise about them if they are out. (AT&T and SuperMedia have them.)
However the US market is much more competitive generally that other markets around the globe and there are a wide range of sources of free local business listings data, including CityGrid, Google, Facebook, Foursquare, Factual, SimpleGeo, de Carta and others. This is on top of the three “mother databases”: Infogroup, Localeze and Acxiom.