On one of my rare visits to Twitter, I did spot a fantastic bit of news. With the release of IE10 on 26/10/2012, Google Apps will be dropping support for IE8 from 15/11/2012.
So where does that leave the various operating systems that run a version of Internet Explorer?
For Windows XP SP3, support for your operating system ends on April 8, 2014. If you were running the 64 bit version of Windows XP, then the latest release was SP2, and support for that ended on July 13, 2010. You can't upgrade to IE9, so your best bet for a modern standards compliant browser is Chrome or Firefox.
For Windows Vista, it's a bit trickier. Current documentation generally states April 11, 2012. But support for SP2 ends 24 months after the release or at the end of the products support lifecycle, whichever comes first. Considering that SP2 was released on April 29, 2009, the support should have ended April 29, 2011. Either way, you can still use IE9 to get some HTML5 functionality, but if you're going to hold on to your Vista release for as long as some folks are holding on to their XP releases, you also might consider installing Chrome or Firefox.
For Windows 7, mainstream support is expected until January 13, 2015 and extended support ends January 14, 2020. You'll also be able to upgrade to IE10, but frankly, why should you have to wait until a major release of a browser that is really aimed at another operating system, before you can get access to the features of a modern standards compliant browser. That's right, get Chrome or Firefox anyway.
For Windows 8 users, I guess you're running the Release Preview at the moment, and will be able to get the full retail version on October 26, 2012, the same day that IE10 is released. If you're sticking to IE, then you can expect two major upgrades to your web browser with the next two releases of Windows at approximately 3 year intervals. Or, you can start using Chrome or Firefox now, enable the sync feature and have extensions install automatically to your Windows 8 installation of the browser.
I haven't covered older releases of operating systems or servers here, but things are getting pretty grim if you're still running Windows 2000, or Windows Server 2003. I don't think Chrome is supported for those operating systems, and details for the latest release of Firefox are hard to find. Firefox 14 is supported for Windows Server 2003, but it's not the latest release at the time of writing. The link provided is for Firefox 14, at the time of writing.
Personally, I'm sticking with Chrome. It's proven to be pretty good for my development needs, but I always keep an installation of IE and Firefox around. I should also keep an install of Safari for Windows around as well, for times when I want to run different logins to the same development site at the same time, and maintain the consistency of WebKit rendering. I'll probably upgrade my IE9 install to IE10, and hope that it maintains the render as features that IE9 does (or I'll check someone elses IE10 install first).
Update: Went looking for Safari for Windows, but it seems that Apple pulled support and all but one link for Safari 5.1.7 for Windows. Maybe I'll use Opera instead. When I need to.