Selecting Directions allows you to enter locations for downloading driving directions from Google Maps.
iPDA provides direct access to the Google Maps page so you can make sure you get the directions you want. When you have the directions, select Transfer to transfer the directions text to your iPod. Note that your iPod must be connected to your Mac to transfer the directions and there is now capability to sync directions.
The directions are listed in your iPod's Notes. Each set of directions is named based on where you are going so that it's easy look up particular directions (especially if they're all from the same location).