Adobe isn't the only company being tempted by the sweet taste of HTML5; Microsoft has a hankering for the stuff too.

Despite its past efforts to shape Silverlight into the leading cross-platform runtime for the web and the desktop, Microsoft now says that its strategy and plans for Silverlight have "shifted."

ZDNet's Mary-Jo Foley spoke with Bob Muglia, the president of Microsoft's server and tools business, about the lack of focus on Siverlight at the company's Professional Developers Conference this week.

Muglia's response was pretty telling. Although he reaffirmed Microsoft's commitment to making Silverlight the development platform for Windows Phone, he noted that the cross-platform solution Microsoft sees going forward is HTML.

Speaking with Foley, Muglia said, "HTML is the only true cross platform solution for everything, including (Apple's) iOS platform."

This is a big admission from the company that has spent years trying to push Silverlight as a cross-platform technology forward. As a video technology — indeed even as an application technology — Silverlight and WPF are actually pretty nice. I attended a two-day XAML workshop held at Microsoft's Atlanta offices in 2009 and was very impressed with the capabilities and the toolsets that were possible within Silverlight.

However, despite the prevalence of the .NET platform on Windows and in the enterprise, Silverlight has had a problem gaining traction across the web. With the exception of the Olympics and a few other live broadcasts, you almost never see Silverlight used on the web.

Likewise, the number of desktop applications built using Silverlight are nascent in comparison to the growing number of Adobe Air applications. Aside from Seesmic Desktop, it's hard to think of any cross-platform apps that are built using Silverlight.

All the while, Microsoft is increasingly embracing HTML5. The company's recent launch of Internet Explorer 9 beta was promoted using a number of different HTML5-specific web pages and promotions. Silverlight may not have been mentioned much during PDC, but HTML5 certainly was.

It's clear that Microsoft — like Adobe, Apple and Google — see that HTML5 is the technology that will work across the broadest stretch of devices — and more importantly, will work on future devices.

Yes, the W3C has stated that the HTML5 spec isn't yet ready for full use, and in a broad, global sense, this is true. However, when you look at the types of devices that individuals will be buying today and tomorrow, and not the device they already own, it's clear that HTML5 is the technology that is going to have built-in support.

As a technology, Silverlight has a lot of promise and we think it is still interesting. Still, we can't help but think Microsoft is making a better strategic move to focus on HTML5 as its cross-platform solution going forward.