Salesforce.com has just released browser usage statistics for its service which is interesting in that the company's clients are enterprises. What this shows is a much more conservative picture than we are used to: 51.7% of users are still on IE 6 even though IE 7 was launched in October 2006.
As web usability guru Jakob Nielsen points out in his Alertbox newsletter, web users are becoming more, not less conservative. The upgrade speed, which was 2% per week historically, has now dropped 1% per week with the latest browsers, he says.
it now seems to take about two years to move most of the users to a new browser version.