With the post, Muglia was responding to the reaction to an earlier interview he had done with ZDNet’s Mary-Jo Foley, in which he described Silverlight primarily as a development platform for Windows Phone 7. He downplayed its cross-platform capabilities, characterizing HTML5 as the tool of choice for cross-platform developments instead.

“Our strategy has shifted,” he said in that interview.

Microsoft had originally developed Silverlight as a platform for building Rich Internet Applications (RIAs). An alternative to Adobe Flash and Flex, Silverlight could be used to build applications that would run, with the aid of a plug-in, across different browsers, and would offer capabilities that HTML itself could not provide.

But Foley, and others, had noted Silverlight’s low profile at the company’s Professional Developers Conference (PDC), held last week in Seattle. There, Microsoft CEO Steve Ballmer only mentioned it once during his keynote speech, while at the same time praising HTML5’s cross-platform capabilities. Also, the PDC itself did not have that many sessions devoted to Silverlight.

For many, this lack of a presence was just the latest and most definitive sign that Silverlight’s future itself was in jeopardy.

Not helping matters was the fact that Microsoft has not announced a release date for the next version of Silverlight, version 5. In a series of widely read blog posts and Twitter updates, Web designer Scott Barnes, a former Silverlight product manager, has speculated that Silverlight is losing favor within Microsoft itself, perhaps due to the fact that its cross-platform compatibility could be a threat to the Windows dominance of the desktop.

Forrester Research analyst Jeffrey Hammond said the reaction to the ZDNet interview was “a tempest in a teapot.” On Twitter, within a matter of a few hours, “It went from ‘our strategy is shifting’ to ‘Silverlight is dead,’” he said.

In his blog post, Muglia attempted to dispel the gloomy rumors. He described Silverlight as Microsoft’s platform for building Web-based applications that can run across different Microsoft platforms, either on the desktop or on a mobile device. “The purpose of Silverlight has never been to replace HTML, but rather to do the things that HTML (and other technologies) can’t, and to do so in a way that’s easy for developers to use,” he wrote.

Even before Muglia’s blog posting, analysts were skeptical of the idea that Microsoft was killing off Silverlight.

“Silverlight is extremely important for Microsoft, because it may be Microsoft’s best way to take the native client development for Windows forward to a Web architecture,” said IDC analyst Al Hilwa, who oversees application development software.

Hilwa noted that when Microsoft released Silverlight, the company did not expect that such a wide range of mobile platforms would be available within a few years. “We have a world with many more platforms and form factors,” he said. Now, Microsoft would probably not be interested in porting Silverlight to all these platforms, though Silverlight still makes sense for bridging different Windows platforms, Hilwa said.

“There are still a lot of Web applications deployed inside of enterprises that are running on Windows platforms,” Hammond said. “Those organizations that have large libraries of .NET applications will continue to use Silverlight, because it represents an easier way to deploy those applications compared to a full .NET client.”