You'd hardly notice the difference unless you were looking for it. MapQuest's latest API is a reinvention of its MapQuest API to display maps. So, what's new? Following the company's recent pattern, MapQuest Open API is based on OpenStreetMaps, the crowd-sourced map favored by many modern geo-hackers.
Previously MapQuest released open versions of its HTTP web services, most recently launching a bike routing API. The company has also been rolling out open versions of its user-facing websites for individual countries. At this point, development open open services seems to be in parallel with its standard services, which are based upon commercial map data. It's possible that MapQuest is testing the OpenStreetMap waters to potentially replace data licenses that are no doubt costly. To that end, MapQuest has dedicated $1 million to "open-source mapping’s development."
It's exciting to see the online mapping trailblazer take an open approach. MapQuest Open joins CloudMade (founded by OpenStreetMap founders) in providing a mapping display service based on OpenStreetMap. Our directory now includes 9 OpenStreetMap APIs.