Last week the Air Force transitioned to the new AEP ground station software that I had been working on at Lockheed for the last 4 years. The transition went smoothly which is really a testament to everyone that slaved away to make sure everything worked. And this really was hard... the tried and true analogy being its like changing the engine when the car is doing 60mph down the highway. You had to be absolutely sure you weren't breaking the system or degrading the accuracy because so many critical systems (both military and civilian) depended on it.
Its actually really cool to know that code I wrote and developed is now being used by the Air Force for the next 10 years or so. Its a very satisfying feeling. I wish I could have been there when they transitioned, after supporting all the test and rehearsal events out at Schriever AFB (those events, while stressful and incredibly long hours, were always a lot of fun too), but the schedule had slipped so that transition was a few months after we moved out to CA.
I still have a stamp on at least the next two rounds of upgrades as well, so hopefully those go as well as this =)