“In conjunction with his self-professed affinity for sharing source code, John Carmack has open-sourced most of the major id Software engines under the GPL license. Historically, the source code for each engine has been released once the code base is 5 years old.”
Wikipedia article: id Software

Photo "cmd.exe" cc by-sa flickr user n3wjack

I think this is a novel approach, and I’m surprised that I haven’t heard of any other companies making this sort of commitment. Fellow open source zealots would warm up to you and you’d earn the love of developer communities everywhere. It also increases the chance that your software has a greater legacy.

Let me know if you’re committing to opening the source of aged versions of your proprietary software. Will it be 2, 3 or some other length of years from now?

At first this article left me very upset, maybe because I found it quite persuasive, but then I reflected that for anyone developing and selling proprietary software, Daniel’s is the only position to believe in and promote.