In an email sent to Google Apps Admins, Google Apps team are dropping old browsers support from Google Apps in order to improve their products and deliver more sophisticated features and performance. As a result, in 2010, support for Microsoft Internet Explorer 6.0 as well as other older browsers that are not supported by their own manufacturers will be phased out.
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We plan to begin phasing out support of these older browsers on the Google Docs suite and the Google Sites editor on March 1, 2010. After that point, certain functionality within these applications may have higher latency and may not work correctly in these older browsers. Later in 2010, we will start to phase out support for these browsers for Google Mail and Google Calendar.

Google Apps will continue to support Internet Explorer 7.0 and above, Firefox 3.0 and above, Google Chrome 4.0 and above, and Safari 3.0 and above. If you are still using an old browser somewhere it’s time to change, since it’s no more supported anywhere and Google is making a good step to encourage people using new supported and more secure browsers.
If the Google Apps team delivered more than 100 improvements in 2009, I think this number will be beated in 2010 to deliver the best and most innovative collaboration products for businesses.