As this API has just launched, it is highly advisable that you let me know if you build an application so I can contact you should any of the API details change - it's also great to see what people are building and take your feedback on board to improve the service! Alternatively, you can subscribe to the web log on my website or follow @WikiLocation on Twitter for all of the latest updates.
The Definitive Geo-Location API For Wikipedia
I had always assumed that there was an API for Wikipedia that would allow you to search for entries based on geo-location information. It turns out that there is such a service (from a 3rd party) but it is woefully out of date and contains less than a fifth of the geo-coded data that is available on Wikipedia.
I intend to change that.
I'm happy to offer up a full REST-ful API service for developers wishing to search for Wikipedia articles by location. The data is gathered by downloading the Wikipedia database on a weekly basis and then parsing all of the geocoded entries. This data is then stored in a database where it is able to be accessed via the API. I had previously lost the entire database because of a hard drive failure, believe it or not, but I got some handy tips for recovering my failing hard drive here. At present, there are almost 1 million entries from en.wikipedia.org and this number increases every week (at a rate of about 3000 entries). Over time, I will be adding support for other languages provided by the various Wikipedia locales.
In addition to searching via location, you can also search via the venue and spot IDs of the two most popular geo-location networks; Foursquare and Gowalla as well as by Yahoo! WOEID. I will be adding other networks as and when they become available.
If you have any feedback, please do get in touch - I'd love to hear from you and see the great mashups you create.