Mapquest is beta launching a brand new API for Actionscript, it is the first available native API for Flash and Apollo. It enables complex rich applications with quickly rendered, points and applications. The true native ActionScript 3 approach, unlike Yahoos wrapped Action Script 2, allows a faster runtime. Availability inside the Flex builder helps developers easier access to build apps.
The data available comes from Navteq and TeleAtlas, and gives access to map data, routing, geocoding and search. More information is available at http://company.mapquest.com/mqbs/4a.html .
The first demo is Golf Course Finder with overlays, points of interests and full screen mode. It shows a responsive UI to narrow down your search for the perfect golf course. Zooming out will show you golf courses all over the country, it has the ability to keep over 10,000 points in memory.
Sadly this cool API is commercial-only for now. Later this year they are planning to make it available rate limited for free. With support for Apollo, I wonder if it will have any offline mode.
Updated: Some private links were accidentally posted. They were removed. You can find out more about the API here.