Overnight, microsoft.com has suffered an outage of a little over an hour. Microsoft have posted to the effect that this was caused by a [presumably non-http] denial of service that is not associated with any known vulnerability in Microsoft's own software. Speculation on Information Week that the outage might be part of a broader attack on internet infrastructure or linked to the start of the Defcon conference seems implausible, as only one other Fortune 100 site has shown an outage in the last 24 hours. Three of the 52 leading hosting providers monitored by Netcraft are showing outages in the last 24 hours, but all three are outside the US.