On HumanamuH I'm using "yyyy-mm-dd" or "mm-dd hh-mm" wherever several dates are displayed in a column (e.g. chat messages or notifications). I think it's easier to see where the day or month changed and it's sorted intuitively. But...
Several people who registered from the US stumbled over the form that lets you enter your birthday in "dd-mm-yyyy" format. Even though the format is explained right behind the form field. They were probably just as irritated as the majority of the world is by "mm-dd-yyyy". Not sure if using "yyyy-mm-dd" for birthdays works better internationally.
Maybe changing the format depending on the IP address would reduce confusion. Of course, users could also have an option to localize their date formats, but I assume most wouldn't want to bother.
By the way, the article contains Wikipedia's map of "Date format by country" which answers your question why nobody is using the ISO format for dates (some do):
Several people who registered from the US stumbled over the form that lets you enter your birthday in "dd-mm-yyyy" format. Even though the format is explained right behind the form field. They were probably just as irritated as the majority of the world is by "mm-dd-yyyy". Not sure if using "yyyy-mm-dd" for birthdays works better internationally.
Maybe changing the format depending on the IP address would reduce confusion. Of course, users could also have an option to localize their date formats, but I assume most wouldn't want to bother.
By the way, the article contains Wikipedia's map of "Date format by country" which answers your question why nobody is using the ISO format for dates (some do):
http://en.wikipedia.org/wiki/Date_format_by_country#Map