We use the "edit in datasheet" when entering data into a list, and we're having issues with fields having the type "person or group".
When entering a user, we have to enter the user's name. However, some users in our company have the same name. Here's an example http://dl.dropbox.com/u/20749284/ScreenShot184.gif
This makes it impossible to correctly identify the correct user. I've tried using an Active Directory user account and an email address. The field only takes a user's name.