From Linux Watch's report on IDC's Open Source in Global Software: Market Impact, Disruption, and Business Models:

The study, which analyzed IDC surveys from over 5,000 developers in 116 countries in the spring of 2006, found that developers worldwide are increasing their use of open source. IDC found that open source-software is being used by 71 percent of the developers in the world and is in production at 54 percent of their organizations. In addition, half of the global developers claim that the use of open source is increasing in their organizations.

I expect this number to grow even larger. The whiz kid programmers and technologists of 20-30 years ago all fought to create and sell the ultimate proprietary software app. Legends Bill Gates and Steve Jobs grew out of this generation. The new generation is no longer thinking hide the source code in binary format, own it, and sell it, but sees the value of collaboration through open source for creating the latest, greatest software. That is, if software patents don't get in the way (sigh!).