A couple years ago, Google had an interesting idea: what if we could make an embeddable version of the Chrome browser that could runwithin older versions of Internet Explorer? Thus,Chrome Frame was born: the browser add-on brings all the HTML5, JavaScript performance, and modern standards capabilities of the Chrome browser to older versions of Internet Explorer. Chrome Frame offers a workable solution for for companies and organizations that are still stuck on (say) Internet Explorer 6 but who need to tap into things like Google Docs and other services that have dropped support for older versions of Internet Explorer.
However, one problem with Chrome Frame is that it required administrator privileges to install—and if you’re in an environment that’s still mandating you use Internet Explorer 6, the odds are pretty good you’re also locked out of administrator mode on those Windows machines. So Google has been working on a version of Chrome Frame that can be installed without requiring administrative access—and now Google has promoted it from beta status to a stable release, and it’s available for free download.
Google says it will shortly roll out a change to the default Chrome Frame installer so it will run at Admin level by default, but will fall back to the Non-Admin mode if a user doesn’t have the necessary permissions—that way there will be a single installer anyone can use to install Chrome frame.
To invoke Chrome Frame, Web developers need to set a flag for it in their sites and services. At the moment, the primary services that support Chrome Frame are (naturally) Google’s own—for instance, Gmail prompts visitors using IE6 or IE7 to install Chrome Frame—but a number of third party sites and services have also added support for Chrome Frame rather than lock out people with older browsers.
[Source]