Google updated Chrome Frame, a plug-in that embeds the company's Chrome browser engine into rival Microsoft's Internet Explorer, to a beta version.
Chrome Frame debuted last September, prompting rivals Microsoft and Mozilla to blast the move. The open source plug-in can be used with Internet Explorer 6, IE7 and IE8.
The beta is powered by the current beta version of Chrome for Windows, 5.0.375.62, but will be updated as Chrome is refreshed. Additionally, the "dev channel" edition of Chrome Frame was revamped today to keep it in sync with that build of Google's browser.
"Chrome Frame is an attempt to move the Web forward," Alex Russell, an engineer on the Chrome Frame development team, told Computerworld. "We're excited that it's ready for broader use and want to get it out there to target [users] who aren't able to use HTML5."
HTML5, the still-under-construction next generation of the Web's foundation language, has become a flashpoint -- and buzzword -- in the increasingly competitive browser market as makers rush to support the standard, especially its video tag that lets Web site designers embed video.
Apple, for example, has been aggressively promoting HTML5 as a substitute for Adobe's Flash, which Apple has banned from its iPhone and iPad.
Meanwhile, Microsoft has been trumpeting the support for HTML5 it's baking into IE9, which has no firm release date and is now at a rough developer preview stage.
Google has been promoting HTML5 just as hard. Last month, for example, Google debuted a new royalty-free video codec that will compete with the H.264 codec that Apple's backing for HTML5.
"We'd like to keep everyone bunched toward the front of the [standards] compatibility edge," said Russell as he further explained why Google is pushing Chrome Frame.
Even though Microsoft is working on IE9, and promising that its next browser will support HTML 5, the problem is that users often stick with outdated versions of IE for years, added Russell.
"And the fact that Microsoft's chosen not to support IE9 for older versions of Windows, like Windows XP, means that IE8 is the end of the road for [XP users]. They'll be in the same situation [in the future] as IE6 users are [now]," he said.
Microsoft may be pushing to end IE6's reign, but it's not conceding anything to Google. Last week, Ryan Gavin, Microsoft's director of platform strategies and the executive in charge of driving down the aged browser's market share, claimed that IE8 was gaining more ground that Google's Chrome in the U.S.
"We're already seeing Chrome in retreat," Gavin said.
Contrary to fears expressed by Mozilla executives last year when Chrome Frame debuted, Google has no intention of releasing a similar plug-in for Firefox, Russell said.
Although such a plug-in is possible, he said, "We didn't release it [and] it's not something that we expect to use."
And Russell dismissed Microsoft's complaints of last year, when IE's maker argued that Google Frame would effectively double users' security problems because they would have to keep two browser platforms up to date.
"The real problem is that Web developers have to target the lowest-common denominator," Russell said, citing the example of the nearly-nine-year-old IE6.
More modern browsers are available, but many users -- for whatever reason -- choose not to upgrade. "Chrome Frame helps those people get the features their browser doesn't support, and installs a better browser within something they're familiar with," he said.
Russell declined to disclose how many users have downloaded Chrome Frame or are using it regularly, but said some major sites and services, including Meebo and Wordpress, have been adding the necessary HTML metatag to automatically switch on the plug-in when it recognises it installed in IE.
The beta of Chrome Frame can be downloaded from Google's website.