I don't think this is at all newsworthy. Alexa is a highly unreliable metric which depends on users suckers installing a "spyware" toolbar. Last time I looked they did not have a version for any browser other than Internet Explorer, and there are now a significant number of people using other browsers such as Firefox.
More realistic data is available from ComScore, but you have to pay to get the latest reports when they are published; otherwise you're working off stale data.