MapBox is a suite of open source mapping tools. The MapBox iOS SDK can be used to create interactive map-driven applications for iOS devices. It also allows users to host their maps so that they can be embedded on webpages and shared with a wider audience. All maps created using MapBox are compatible with Android and iOS devices.
Zillow has released an application for iPhone users that builds on their Zillow API, the Microsoft Virtual Earth API and the iPhone's GPS capabilities. The Zillow iPhone app detects your location and shows data about nearby homes, including market values, photos, and which ones are for sale. It's a great example of a mobile mashup application that uses multiple APIs in meaningful location-aware context.
Yesterday, Yahoo announced its new Internet Location Platform API, "a resource for managing all geo-permanent named places on Earth" that "provide[s] the Yahoo! Geographic Developer Community with the vocabulary and grammar to describe the world's geography in an unequivocal, permanent, and language-neutral manner."
Localscope, the app that:
"lets you see and know your locality like never before," now "enables third party applications to use the Localscope app to search for and discover geo tagged information via the Localscope API."