Google has announced that Google Docs will drop support for Microsoft's nearly nine-year-old Internet Explorer 6 (IE6) browser starting on March 1.

Ironically, if Google had taken its anti-IE6 advice to heart before hackers broke into its corporate network last year, it might not now be mulling whether to abandon the Chinese search market.

"We're going to begin phasing out our support, starting with Google Docs and Google Sites," said Rajen Sheth, senior product manager for Google Apps, in a Friday entry on the company's enterprise blog. "As a result, you may find that from March 1 key functionality within these products -- as well as new Docs and Sites features -- won't work properly in older browsers." Google Sites is the search engine's free Web hosting service.

Google's new list of supported browsers omits IE6, as well as other older programs, including Mozilla's Firefox 2.0, Apple's Safari 2.0 and Google's own Chrome 3.0. IE6 is by far the oldest browser of the bunch, with an August 2001 debut. In comparison, Firefox 2.0 dates to October 2006, Safari 2.0 to April 2005 and Chrome 3.0 to September 2009.

People running older browsers should upgrade to a newer version, said Sheth, who posted links to downloads of IE8, Firefox 3.6, Safari 4.0 and Chrome 4.0. The latter is available in final form only for Windows; Chrome 4.0 for the Mac is still in beta.

Google's move is only the latest in a year-long string of major Web properties dropping support for IE6 or urging users to ditch it for something newer. The campaign began in February 2009, when Facebook prompted IE6 users to upgrade. It then accelerated last summer when Google's YouTube did the same, as Digg announced it would curtail IE6 support and as a California site builder led nearly 40 Web start-ups to urge their users to dump the browser. An "IE Must Die" petition on Twitter, meanwhile, has accumulated more than 14,000 signatures.

Even Microsoft beat the anti-IE6 drum, although it has also admitted that the job is difficult because the old browser is still mandated by some enterprises. IE6 also accounts for half the browsers used in China, according to recent data from metrics company NetApplications.com.

Microsoft has promised to support IE6 until April 2014, when it wraps up all support for Windows XP, the operating system tied to IE6.

Google's own use of IE6 allowed hackers to break into its company network late last year and make off with an undisclosed amount of the company's intellectual property. The attacks, which used an exploit of a then-unpatched vulnerability in IE6, showed that Google and dozens of other major Western companies were running Microsoft's ancient browser.

Google claimed it had proof that the attacks originated in China. Since then, security researchers have offered clues that appear to confirm Google's accusation.

According to NetApplications, IE6 use has slid dramatically in the past year. Last month, the browser accounted for 21% of the global usage market, down from a 34% share in December 2008.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, send e-mail to gkeizer@ix.netcom.com or subscribe to Gregg's RSS feed .