A user in the UK has set up a milestone for Dec 15th. It shows up in the web interface correctly as this:
Version 4.8 Code Freeze: 15/12/2009
However it is one day off in email notifications about cases:
Version 4.8 Code Freeze: 12/14/2009
The date is one day off.
Note that it is also using U.S. date formatting (month, day, year) instead of UK (day, month, year)