Start a wiki on your network using some wiki software.
Start a category on your site called "best practices" or "coding standards" or something.
Point everyone to it. Allow for feedback.
When you do releases of the software, have the person whose job it is to put code into the build push back on developers, pointing them to the Wiki pages on it.
I've done this in my organization and it took several months for people to really get into the hang of using the Wiki but now it's this indispensable resource.
