Microsoft believes HTML5 is "the future," Sardo said. It has implemented parts of the standard -- which is not yet complete -- in IE8, and will fully support it with IE9. Microsoft released its second developer preview of IE9 on Wednesday morning, he said, though he didn't say when the final product will ship.
He also said Microsoft tries hard to keep people's browser software up to date. For example, it allows PCs to download browser updates even if the copy of Windows is unlicensed. This is especially important in China, where a lot of software in use is pirated.
"One of the main challenges at Microsoft is the complexity of adopting a new spec," Sardo said. HTML5 is "a great spec and it will lead to a great future for developers, but it's still a work in progress." Ensuring the implementation is the same across all browsers involves "a lot of work to test and validate."
Eich said Mozilla has "got a lot of HTML5 already implemented, even though it's a moving target."
Crockford proposed a radical solution to get all the Web's users onto a current browser: On an agreed-upon day, all developers would deny access to their Web sites unless the visitor's browser is up to date.
"On one day, all of us will say, you have to download one of these five or six browsers," he said. "I propose that day is 30 days after all the major browser vendors have implemented HTML5. On that day, IE6 dies."
It may not have been a very practical idea, but it earned him a round of applause from the developers watching the discussion.