I've been planning to do the same thing.
In my mind, I'm trading a little added weight for better braking performance. I'm sure plenty will come out and argue that you don't NEED a disc brake. I have discs on my geared commuter (Salsa Las Cruces) and no, I don't NEED them, but I most definitely want them. Since the fixed-gear has become my primary commuter, I'm more motivated to go ahead and swap to a disc compatible fork. The only potential issue is matching rake to your existing fork - or dealing with the new ride characteristics.
I've never seen that Airborne fork before. I've been keeping a list of available disc road forks here:
http://www.bikeforums.net/showthread.php?t=270819