JP has written up an interesting post, Build versus Buy versus Opensource. He argues that these are the three options that IT has when it comes to software. I would change these options to build, acquire, or consume and would also argue that these options are not mutually exclusive. Customers could build a system that runs on open source software and could pay for commercial support for the open source software and could integrate with a proprietary, free, but non-open source software. You get the point. It's intertwined and most of the times customers do combine the options and that's why I would say build when you have to on top of what you acquired (free or open source) and consume (services) whenever you can to avoid both. There are obviously other factors IT considers when they pick software and its deployment model but I don't see the world as black and white as open source and non-open-source. Though I see plenty of opportunities to structure and sell software to minimize the "build" part on the IT side - personalize against customize.
I really liked what the V.P and Chief Marketing Officer of GE shared during their China Olympic sponsorship efforts. He said "Our number-one revelation is that customers don't necessarily organize their buying behavior the way we structure our business." I could not agree any more and this is applicable to software as well.