Jason Whittington has some comments on Joel's Lord Palmerston essay, on how programming has gotten harder. He comments that

Personally I think the heyday of  really hard programming were the early 1960s, when the first big distributed electronic commerce systems like SABRE were being built.  American airlines contributed the 1960 equivalent of a billion dollars to build SABRE over 5 years (I don’t know what other airlines spent).  I believe these numbers and timeframe are similar to what Microsoft spent to develop the entire .NET platform.  It’s hard to believe that if the airlines wanted to build a reservation system today they couldn't use mostly off-the-shelf software and get it done for 1/10 that cost (or less, I’m an optimist).  Even if it feels like you have to run to stand still in this industry I think it's easier than ever to get things done.

Talking about the travel industry is always a good way to get me to pay attention ;-) If you want a good read on the construction of SABRE, chapter 2 of the book Hard Landing has the story. In fact, Sabre was the 2nd system American Airlines tried, another company (Burroughs, IIRC) tried and failed before IBM succeeded. I still work in the industry, and the amount of effort involved in making changes on the mainframe is absolutely incredible. One of my co-workers who's worked on the mainframe tells me that he used to maintain code where the last modification date was before he was born.  Now that's legacy code.