Microsoft is crying foul over recent comments made by an Adobe executive that Silverlight has "fizzled" as a competitor to Adobe's Flash.

In his blog, Tim Sneath, director of the Windows and Silverlight technical evangelism team, accused Adobe Executive Vice President and CFO Mark Garrett of "living in a fantasy world" if he thinks that Silverlight adoption is waning.

"The idea that Silverlight is in anything other than rude health is more to do with what Adobe would like to be the case, rather than what actually is the case," he wrote in the blog posting. "The suggestion that 'Silverlight adoption has fizzled out in the last 6-9 months' is pretty risible, in fact. For starters, Silverlight 2 shipped four months ago, and in just the first month of its availability, we saw over 100 million successful installations just on consumer machines. That doesn't sound like 'fizzling out' to me."

Sneath was responding to comments Garrett made when answering a question about Silverlight and the competitive landscape at the Thomas Weisel Partners Technology & Telecom Conference 2009 in San Francisco on Tuesday. In his comments, confirmed Thursday by an Adobe representative, Garrett said Silverlight adoption was strong when the technology was right out of the gate but has tapered off in the past six to nine months.

Sneath's reference to Silverlight 2, the second version of the technology, is key to his defense of the technology. Silverlight, which comprises a tool for developing and designing Internet applications and a media player for delivering content, was first introduced in 1.0 version in April 2007. However, it wasn't until the release of Silverlight 2 that the technology was fully baked and became truly viable as an alternative to Adobe Flash.

But Microsoft has lost customers when Silverlight didn't live up to its expectations, even after Silverlight 2 was released. MLB.com, which switched from Flash to Silverlight to stream live baseball games beginning in August 2007 with Silverlight 1.0, said in November—a month after 2's release—that it was dumping Silverlight and had signed a two-year deal with Adobe to use Flash again for live streaming.

That said, some high-profile Web sites have used Silverlight 2 to live-stream some notable events recently—the inauguration of U.S. President Barack Obama last month and the 2008 Summer Olympics in August among them.

In his post, Sneath pointed out some other recent high-profile Silverlight customers, not just in the U.S. but also overseas. In the U.S., both Netflix and the Home Shopping Network launched on-demand services that use Silverlight, he said. In Europe, satellite broadcast network Sky launched a video-on-demand service using Silverlight in December, and the technology also is being adopted for television broadcasting portals in Japan and Korea, Sneath added.

But Flash has had a significant head start and adoption of the technology remains strong, according to Adobe, which has been doing some touting of its own, lately not just about Flash but also about a new technology, Adobe Integrated Runtime (AIR). AIR allows developers to use the same tools with which they build Web-based applications to create desktop apps.

Two weeks ago, Adobe said the newest version of Flash, Flash 10, was installed on more than 55 percent of computers worldwide in the first two months of its release and is expected to surpass 80 percent adoption by the second quarter, the fastest installation rate of any versions of the technology. Moreover, AIR has reached nearly 100 million installations in less than a year after release.

Flash is actually gaining momentum since Microsoft released Silverlight, according to comScore research for 2008 that shows Flash increasing its worldwide share of video on the Web from 66 percent to more than 80 percent.

Also, although Silverlight has scored some high-profile Web sites as customers, enterprise developers have said its adoption among businesses—a scenario in which it actually has an advantage over Flash because of Microsoft's historical strength in that market and the ability of developers to use .NET tools to build Silverlight applications—has been lackluster.

Developers cited Silverlight 2's launch during an economic recession—when businesses, particularly enterprises, are hesitant to adopt new technologies—as a factor hampering its adoption.