* This post is updated. There are some corrections, since the licensing terms on the website seems to have changed. There is now an 'Express' license, which is not included in the License Matrix (as on 17.04.07) which I checked for writing the post earlier. It might be that the matrix in not updated for Community Server 2007 yet. Thanks to 'anonymous' for pointing out that there is such an Express license.
I have been seeing Community Server for a long time now, since it is possibly the most widely installed Content Management System (CMS) in Asp.Net. Among the big plusses are ease of use and simplicity in deployment and maintenance. You could argue that it is the best CMS available on Asp.Net, and most of Microsoft's own community sites (like asp.net, netfx3.com) are now running on Community Server.
All good, until I visited their site today morning.
Last time I checked out Community Server (v2.0), it allowed full commercial usage if the Community-Server logo and its link back to the parent website was provided in every page. Even if that was not ideal, you could live with it since the image was sitting at the bottom and generally harmless. The license also does forbid you from creating a derivative work.
Here is the old FREE license:

For the instances where I suggested Community Server earlier (2005-06), these restrictions seemed OK. It was better than closed source, you could use it free-of-cost and the source was available, though you could not re-package and sell it. I respected their business model; I thought it was just different. It was cleanly somewhere between a fully Closed Source application and an Open Source application.
Today morning, I had another requirement for a community site (with a Microsoft platform restriction) and Community Server was the first thing that came to mind. When I checked out the new Community Server Edition (Community Server 2007), I noticed there were some licensing changes. The version comparable to the old license is now called ‘Personal' edition (Personal License), but it fully excludes commercial use. The new ‘Express' version allows commercial use (Express License), but only on the intranet. It also has a limitation on the number of blogs (limited to 10), and number of forums (limited to 15). This means you cannot use it on a moderately sized intranet as well.
While I can stop whining and choose an alternative for the new website, I am wondering what the older Community Server users (who do not prefer to buy a commercial license) will do. They have no upgrade path, and are stuck with an unsupported version. That is bad.
License changes screw customers.
There is a lesson to be learnt from the Community Server story, that Open Source is not Open Source until it holds true in ‘spirit'. Unless it gives full modification and re-distribution rights to the users, it is not much better than Closed Source. In some ways it is even worse, because when you are buying Closed Source you know it is closed and that you are screwed if the company wishes to do so. With Restricted-Open-Source, we tend to lean comfortably on the ‘Open'ness, willing to live with its restrictions. It might bite back hard.
To restate the obvious, if this was a real Open Source application and there is such a license change, a fork would have evolved in less than a week.
So, that's how I learnt to trust only _REAL_ Open Source.
*The licensing restrictions may have been introduced in any version after v2.0, and not with the latest version.
Update: My concern is not with a restrictive License, it is with the License _change_. I totally appreciate a company's right to choose any license it wants to. Or the larger lesson from this is to never take anything for FREE unless it is a true Open Source license.