Adobe on Monday announced the availability of its AIR technologies, which aim to bridge the gap between Web applications and true PC-based software. These types of applications are considered a major stepping stone to the coming era of so-called cloud computing. It's most sophisticated competitor is the recently launched Microsoft Silverlight, which utilizes the company's .NET technologies to provide next-generation interactive experiences on the Web.

"Adobe continues to advance the future of digital experiences by enabling our customers to create highly interactive, expressive applications," says Adobe CTO Kevin Lynch. "This is an exciting time for Adobe, for innovation in software, and for designers and developers who are driving the Web forward."

While both Adobe and Microsoft are trying to bridge the gap between Web applications and desktop applications, their approaches are somewhat different. Microsoft's Silverlight is designed to be accessed from a Web browser, and it provides rich media and Web application capabilities that were previously impossible or at least difficult to achieve on the Web. Adobe, meanwhile, is bringing Web technologies to the desktop with AIR: It is basically a runtime engine that allows Web developers to easily deploy Web applications on the desktop and access them while disconnected from the Internet. (Major players like eBay, NASDAQ, Nickelodeon are using AIR to replicate their Web properties on the desktop.) Both technologies support Windows and the Mac.

AIR and related technologies like the Mozilla Prism project and Google Gears are tackling the biggest barrier to cloud computing: Though Web applications are useful and widely used, they cannot be accessed while offline. These technologies are also trying to bridge the worlds of the local PC and the Web so that, for example, you might be able to use a Web application-based document editor to access document files stored on your PC. Or, you could access a Web-based email solution while offline, and have any new emails or replies synchronized when the machine does get connected.

Adobe has also released a related software development kit (SDK) called Flex that specifically targets AIR solutions. Flex runs on Windows and the Mac and a future version will support Linux as well, Adobe says. Both AIR and Flex are available for free. A full-featured Flex development environment, called Flex Builder, costs $250.