There's more background in this interview with Chris Heilmann and Chris Boden on the Yahoo! Developer blog, 'Lonely Planet starts developer program at mashed08 in London', but I thought it was worth pulling out this quote about the benefit of APIs, particularly as they're an organisation whose business model relies on its reputation and content:
Where do you see the benefit in releasing an API? How do you plan to monetize it or is it a loss-leader for you?
We don't have a funky web app like Twitter or Dopplr at this stage but we do have content - in a sense, that content is our platform. We want to take the Lonely Planet content and community experience onto relevant new platforms and make it accessible to travellers in new ways. We're not going to be able to do all of that on our own so we're looking to tap into external sources of innovation and creativity through open collaboration to help us imagine and execute the next generation of services that might enrich the lives of our community.
In terms of monetization, we'll look to work commercially with those developers who come up with innovations that we believe have the potential to create commercial value.