What is open source? How about Open Source?

I saw this today on Slashdot. I’ll admit that there always seems to be some contention here at Microsoft. Even on our team, where we do release source code and allow others to participate in the development on www.codeplex.com, seems to go back and forth.

Are our projects, the Developer Power Toys, open source? We use a fairly liberal license, we allow people to get the code, make changes, contribute back, etc. You can recompile with your changes and redistribute.

How about a project that that publishes the source to a select set of paying customers?

Then there are some that feel there is “Open Source” and “open source” where both mean something different…. A complexity that was noticed by the first commenter to the Slashdot post. Who says: “This is why I don't like Open Source as a term; it is far too misleading. In fact, it doesn't actually mean anything other than the fact there is a mechanism by which you can see the source code that doesn't involve getting a court-order.”

Thoughts?