Just four months after the introduction of its last release of Silverlight, Microsoft has already kick started the testing of the next iteration of the technology designed as an alternative to Adobe Flash. On the second day at the Professional Developers Conference in Los Angeles, Scott Guthrie, corporate vice president of Microsoft’s .NET Developer Platform, announced the availability of the Silverlight 4 Beta, with the download links going live on November 18th, 2009.

It is by no coincidence that Microsoft has chosen PDC 2009 for the launch of Silverlight 4 Beta. According to the company, the first Beta development milestone of Silverlight 4 is a release reserved for developers. In this manner, the software giant is aiming to provide devs with an early preview of Silverlight 3’s successor in order to get them to start building content tailored to version 4 long before it actually becomes available for the general public.

“This is a developer beta release only! This release of Silverlight 4 Beta is a developer release. What this means is that there is no “go-live” licensing available and the end-user runtime of Silverlight 4 is not available. The tools below are intended for software developers only,” Microsoft explained.

While this is true, Microsoft is providing the Silverlight 4 runtime for both Windows and Mac OS X users. It is critical to note that the Redmond company underlined that providing the Silverlight 4 Beta runtimes for Windows and Mac was a move designed to permit developers to run testing machines. As long as a go-live license is not provided, developers will not be able to build Silverlight 4 Beta content and make it available to end users. And after all, there’s no end user Silverlight 4 Beta runtime available yet.

A member of the Silverlight team revealed that Silverlight 4’s “powerful new features offer developers significant benefits in rapidly creating rich software experiences, and include:

• Enhancements to Silverlight out-of-browser capabilities which enable high quality application experiences on the desktop;
• Advancements in business application development, including access to other Microsoft products like SharePoint 2010, Office, and Internet Information Services (IIS);
• The most amazing HD-quality video experiences on the Web with native multicast and offline DRM support.”

Silverlight 4 Beta is available for download here.