Internet explorer 8 has been available for 4 months now and it's had a pretty major impact -- on IE 7.
This is a crude chart, showing just two points, where things were the day IE 8 was released, and where things are today. (data from Net Applications)
As I've said in previous blog posts, browser releases, Microsoft's or any of the other vendors', are having no impact at all on IE 6. IE 6 is on its own trajectory that's probably much more aligned with the PC upgrade cycle and the growth of the Web.
But IE 8 is reaching a lot of IE 7 users and I expect this trend to continue for some time. Users that were willing or able to upgrade to IE 7 are probably going to do the same thing for IE 8. With IE 8's compatibility mode and increased security and standards support, there's really no reason for people who are on IE 7 not to upgrade.
The results are pretty interesting right now. IE 7, the most popular browser version on the planet, accounts for less than 30% of browser usage. IE 6, the scourge of the Web, now accounts for less than 15% of Web usage. And IE 8 has just topped 20% of browser usage.
This is a very different and I think a much improved state of affairs from where things were when we launched Firefox 1.0. Back then IE 6 was the most popular browser with almost 85% of Web usage followed by older IE versions accounting for another 10 points of share, and with all other vendors' browsers accounting for only 5% of usage.