Google has removed the beta tag from Chrome Frame, the Internet Explorer plug-in that turns Microsoft's browser into a Google browser.

More than three months after it was officially released as a beta, Chrome Frame is now officially stable. Beta users will be automatically upgraded to the stable version over the next few days.

Chrome Frame first hit the interwebs as a developer preview in September of last year, as Google expanded access to Google Wave, the now-defunct communication platform that relied heavily on web standards such as HTML5, and required speedy JavaScript and DOM performance. Internet Explorer 8 and earlier versions of Microsoft's browser couldn't quite handle something like Google Wave, and Chrome Frame was Google's effort to solve this problem.

In essence, Chrome Frame equips Microsoft's browser with the rendering and JavaScript engines at the heart of Google Chrome. "Unfortunately, Internet Explorer, still used by the majority of the Web's users, has not kept up with such fairly recent developments in Web technology," Wave founding father Lars Rasmussen and technical lead Adam Schuck said at the time.

"In the past, the Google Wave team has spent countless hours solely on improving the experience of running Google Wave in Internet Explorer," Rasmussen said. "We could continue in this fashion, but using Google Chrome Frame instead lets us invest all that engineering time in more features for all our users, without leaving Internet Explorer users behind."

Internet 9 has finally rescued Microsoft from the dark ages, but earlier versions are still widely used, and IE9 will not be available for Windows XP or earlier versions of Microsoft's OS.

Though Wave is dead, Google is still interested in beefing up older IE browsers for use with other modern web applications. Google services such as Orkut, Google Docs, and YouTube have adopted Chrome Frame, as have third-party sites such as Meebo, WordPress, DeviantART, Hootsuite, and github. Ruby on Rails is also making it the default for all users of Rails apps, and Google says that Gmail and Google Calendar will soon follow suit.

Predictably, when Google IE first arrived, Microsoft was peeved. "With Internet Explorer 8, we made significant advancements and updates to make the browser safer for our customers," the company told us. "Given the security issues with plug-ins in general and Google Chrome in particular, Google Chrome Frame running as a plug-in has doubled the attack area for malware and malicious scripts. This is not a risk we would recommend our friends and families take."

Yes, this was mostly FUD. But just days later, Mozilla bitchslapped Chrome Frame as well — and its arguments actually stood up. Mozilla vp of engineering Mike Shaver explained that Chrome Frame sidestepped IE's built-in security tools, and he argued that it would end up confusing netizens.

"The user’s understanding of the web’s security model and the behaviour of their browser is seriously hindered by delegating the choice of software to the developers of individual sites they visit," he said, alluding to the fact that after you install Chrome Frame, individual websites decide when to launch it.

"It is a problem that we have seen repeatedly with other stack-plugins like Flash, Silverlight and Java, and not one that I think we need to see replayed again under the banner of HTML5."

Mozilla boss Mitchell Baker agreed. "If you end up at a website that makes use of the Chrome Frame, the treatment of your passwords, security settings, personalization, and all the other things one sets in a browser is suddenly unknown," she said. "Will sites you tag or bookmark while browsing with one rendering engine show up in the other? Because the various parts of the browser are no longer connected, actions that have one result in the browser you think you’re using won’t have the same result in the Chrome browser-within-a-browser."

With the release of the Chrome Frame beta in June, Google addressed some of this criticism. If you're using IE's private browsing mode and the browser flips on Chrome Frame, Google will turn on a similar setting. The new beta also moves in step with IE cache-clearing and cookie-blocking tools.

Google says that with the stable version, the plug-in now starts three times faster on Windows Vista and Windows 7 and the "most common" conflicts with other plug-ins have been remedied. You can download the plug-in on your own here — whether Microsoft likes it or not. ®