I don't think that's the same as saying Silverlight has been installed on 25 percent of the world's computers. Adobe's market-dominating Flash platform is found on 99 percent of U.S. Internet-connected PCs, according to this June 2008 NPD Group research.

Microsoft also announced expanded support in Silverlight for open-source programming languages. From the outset a year ago, the company has emphasized that Silverlight is a cross-platform, cross-browser platform for increasingly popular and sophisticated online applications.

One of the most significant wins for Silverlight was NBC's Olympics Web site. Microsoft says that during the 17 days of the event, 50 million unique users visited the site and Silverlight's U.S. market penetration grew 30 percent. (Microsoft doesn't say the size of the user base before the Olympics, so it's tough to gauge how impressive, or not, that figure is.)

In any case, this is a key piece of the company's strategy of building a Web development platform.

Guthrie explained the task in an interview in March: "One of the challenges of launching a new browser plug-in is getting deployment ... so that as a Web developer you can just depend on it being there, already installed in the browser."

He said today that the company knew launching a new browser plug-in is an ambitious effort that would take a couple of years to gain significant market share to attract Web developers to the Silverlight platform. Microsoft launched Silverlight 1 about a year ago.

Guthrie hopes several partnerships with major Web sites will help drive adoption. Sticking with its success in sports partnerships, Microsoft announced that CBS College Sports Network is using Silverlight to power 20,000 hours of online college sports video annually.

It was one of several major customers using Silverlight. Others include Blockbuster, Hard Rock Cafe International, Yahoo Japan, AOL and Toyota Motor.

Asked this morning about what's next for Silverlight, Guthrie said he was pleased with the current release and planned to build on top of it. He gave no details of what might be added.

Update, 10:18 a.m.: At the end of the conference call this morning, Guthrie was asked about the prospects for Silverlight on the Apple iPhone and Google's Android mobile operating system and its browser, Chrome. His response:

"We have talked with Apple. We are very interested in being able to run on the iPhone. At the end of the day, Apple ... ultimately controls what software runs on the iPhone. To date, what they've said is they're not at this time looking to enable browser plug-ins like Silverlight or Flash to run on top of it. They might in the future. ... If they let us, we'll definitely come."

Guthrie said Microsoft is continuing to look at Silverlight for Android. "If sales are good," he said, the company will consider it.

Silverlight did not work well on the initial release of Chrome, but a recent update solved the problem and Chrome for Windows supports Silverlight 2, he said. Microsoft has not tested it with the Mac version of Chrome yet.