cocoaforge

Is is possible to set up an Auto-Reply message for a particular contact. Say, my girlfriend gets one message when I am not available and everybody else gets the default or another message.

Yes here are the steps:
1) select the contact in the contact list
2) command - i (Get Info)
3) Select the events tab
4) Create a new event for Message Received by double clicking on it
5) change the action to Send a Message
6) Fill out what you want it to say