Hi Adam - I believe we fixed some issues recently with the date format/field when its displayed on the screen (as that used to be a bug) however we didn't realize this was still a problem for things such as email events and so forth. The date format for some areas is supposed to be in a standard format (like SQL Events, saved to the database in a standard format etc...). We will need to log this for review and a possible fix if its appearing correct on the page but not in the email event...
In the mean time and as a work around you might want to consider using a standard textbox and a jQuery datepicker field which would then save the data as text and work correctly on the screen. If you want to go this route I would check out demo 28 at
http://www.datasprings.com/formdemos. I actually prefer the look and feel to this method better then the built in DNN Date Picker myself.
Thanks,
-Chad