Shrinkwrap software
Before 1980, software was mostly specially written. If you ran a business, and wanted to computerize, you'd typically get a computer and compiler and database, and get your own stuff written. Business software was typically written to adapt to business practices. This is not to say there was no canned software (I worked with SPSS before 1980), but it wasn't the norm, and what I saw tended to be infrastructure and research software.
Nowadays, you can go to a computer store and find, on the shelf, everything you need to run a small business. It isn't designed to fit seamlessly into whatever practices you used to have, but it will work well once you learn to work more or less according to its workflow. Large businesses are a lot closer to shrinkwrap than they used to be, with things like SAP and PeopleSoft.
It isn't a clean break, but after 1980 there was a very definite shift from expensive custom software to low-cost off-the-shelf software, and flexibility shifted from software to business procedures.
It also affected the economics of software. Custom software solutions can be profitable, but it doesn't scale. You can only charge one client so much, and you can't sell the same thing to multiple clients. With shrinkwrap software, you can sell lots and lots of the same thing, amortizing development costs over a very large sales base. (You do have to provide support, but that scales. Just consider it a marginal cost of selling the software.)
Theoretically, where there are big winners from a change, there are going to be losers. So far, the business of software has kept expanding, so that as areas become commoditized other areas open up. This is likely to come to an end sometime, and moderately talented developers will find themselves in a real crunch, unable to work for the big boys and crowded out of the market. (This presumably happens for other fields; I suspect the demand for accountants is much smaller than it would be without QuickBooks and the like.)
