Release 1.0 supports the ability for maps to be configured where the markers information window is rendered in tab format.  The first tab is the basic information from the marker.  The second tab, labeled "Directions", provides for someone to enter the starting address.  Once the user presses go, a new window will open and provide driving directions from Google.

This functionality is configured in the "manage maps" section.  When you edit a map, the you will see a third tab labeled "Markers".  On that tab, there is a parameter that can be set to enable directions.  Set that to YES and you are good to go!