DD/MM/YYYY – do people know what that means?

Just finished reading Caroline Jarrett and Gerry Gaffney's Forms that Work and I noticed that while the publisher used a screen shot on the front cover with that date format the authors didn't actually tackle the issue of DD/MM/YYYY in the book ... which provoked discussion about it when we reviewed the book at UX bookclub earlier this week.

Has anyone tested the use of the DD/MM/YYYY format string to communicate to users how to enter a date in a single or even triple text field? Or have you found it's easier just to provide year and month drop down lists?

What about for credit card detail forms where the input format must match the card so you have to use numerical dates in MM/YY format?

What are some alternatives that allow quick date input with text fields and also ensure the correct order?