I know Google has this reminder sent in random to its users but I'm still sharing it, anyway in case you may have missed checking yours. Here's the full content of the mail:
We plan to begin phasing out support of these older browsers on the suite and the Google Sites editor . 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 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.
Starting this week, users on these older browsers will see a message in Google Docs and the Google Sites editor explaining this change and asking them to upgrade their browser. We will also alert you again closer to to remind you of this change.
In 2009, the Google Apps team delivered more than 100 improvements to enhance your product experience. We are aiming to beat that in 2010 and continue to deliver the best and most innovative collaboration products for businesses.
Thank you for your continued support!
The Google Apps team