Many sites are reporting about Google knol as a competitor to Wikipedia - I see it as something completely different: An easy way to write down some knowledge that you may have gained, in order to share it with others. My first knol is a copy of one of my blog posts: Win32 thread names in Delphi. This is a kind of information that doesn't belong into Wikipedia, but can be helpful to others.
I can only recommend all programmers to have a look at the knol principle, because it's an easy way to offload information in a way that makes you able to find it again easily, in case that you don't have anywhere else to put it. And maybe somebody will provide extra information that makes you learn more about the topic that you're working on.