AppleInsider reports that Apple detailed their use of a JavaScript framework called SproutCore at WWDC last week.
SproutCore is an "open source, platform-independent, Cocoa-inspired JavaScript framework for creating web applications that look and feel like Desktop applications". Apple also contributed to performance updates and added new functionality to the SproutCore framework, which serves as the basis for their new MobileMe web-applications. Apple describes the user experience for their new MobileMe web applications as Desktop class, providing features such as drag and drop, click and drag, and keyboard shortcuts (guided tour video).
Apple's interest in SproutCore is, in part, to reduce their dependence on Adobe's Flash player, which traditionally is used for more interactive content on the web. Being based entirely in JavaScript, any modern web browser can run these SproutCore based applications without any additional plugins.
Those frameworks offer prebuilt code that has been polished to work on all browsers, making it easier for the developer to concentrate on what their web page should be doing rather than repeatedly reinventing the wheel for various low level functions. In that respect, open JavaScript frameworks can replace Flash without requiring any secondary plugin runtime because they are simply open JavaScript that runs in the browser directly.
Apple has also notably resisted adding Flash support to the iPhone, and made significant efforts to optimize Javascript in future versions of Safari. These improvements should trickle down into the iPhone's mobile Safari as well. This being said, the functionality of SproutCore can not replicate many of the advanced functions of Flash (such as videos and advanced animation).
The article makes the leap that SproutCore represents "Cocoa for Windows" suggesting that Apple may use the tool to develop cross-platform web-versions of its productivity applications, such as iWork, but this appears to be speculative. In a related note, a new startup called 280 Slides has introduced a web-based PowerPoint/Keynote presentation application. 280 Slides was founded by two former Apple employees and also utilizes a Cocoa-inspired JavaScript framework called Objective-J/Cappuccino.