I have my date format set to "Year First (YYYY-MM-DD): https://dl.dropbox.com/u/2071906/screencap1.png
However, when I create an event the hint in the Event Date field uses the Month/Day/Year (MM/DD/YY) format: https://dl.dropbox.com/u/2071906/screencap4.png
It says "The date the event occured (enter date in YYYY-MM-DD format)." right below the field, but the field doesn't seem to use this format.
If I use the built-in calendar to select a date it also uses MM/DD/YY instead of YYYY-MM-DD: https://dl.dropbox.com/u/2071906/screencap5.png
I am able to enter a date in YYYY-MM-DD format, and it will be recorded correctly. It will also be displayed in YYYY-MM-DD format in the display table: https://dl.dropbox.com/u/2071906/screencap6.png
This is a minor issue that doesn't impact the ability to use the plugin. I just figured I'd mention it in case anyone else notices this.