At yesterday's Consumer Electronics Show (CES) Yahoo announced the early preview of their Mobile Developer Platform. This XML-based platform for creating mobile-optimized applications called Yahoo Mobile Widgets will run across a variety of devices and carrier networks. Yahoo wants this to be a one-stop solution for mobile developers and it's another varition of write-once and deploy widely. To help track this platform we've now added an API profile for Yahoo Mobile here.
Mobile development can be quite a challenge due to a combination of technical hurdles like device incompatibilities as well as the business challenges of dealing with carriers. By leveraging Yahoo's installed software mobile developers have an opportunity to get onto the handsets more easily. Note that Yahoo's approach is different than a platform like Google's Android in that they're looking to leverage existing platforms rather than create a new one. Initial launch partners include MTV, eBay and MySpace.
In terms of what's available for the development platform at the moment, you can start with the one page Overview and then move onto the more detailed 44 page Developer's Guide (PDF). Other pieces of the puzzle including the ability to submit your apps for approval and publication to devices is coming soon.