To bring such a phenomenon about, it seems that it will take passing the word around.
The word's been around, many many times. The issue has been discussed to death on sites like newsforge, slashdot, and many others. Every once in a while someone comes up with the "solution" and the complete world domination by LAMP technologies is just around the bend. Other people start groups aimed purely at influencing big businesses and politicians, but these never seem to go anywhere due to lack of funding, organization, and internal disputes.
Ignoring a few of the brainwashed-by-flashy-marketing business types the fact is that many companies have a whole lot of resources invested in proprietary technologies. Even if it would save them money in the long term (often it wouldn't) it would take tonnes of resources (time, money, people) to switch over. Proprietary technology is also far more advanced in certain areas. Open source isn't the solution to everything. It's a lot more complex than switching your home computer over to Linux.