This post is in response to Dario Borghino's story, "Why Open Source is not Free Software". Go read that first...
I have a couple problems with this post. First of all, there is much less difference between free and open source software than this post suggest. Secondly, patents do not have much effect on the software industry, in practice. Those may sound controversial, but let me explain.
First of all, show me an open source license in wide use that is not also a Free software license, and vice versa. See http://opensource.org for the open source definition, and a list of licenses. They are the same thing, but with a different emphasis--"open source" emphasizes the practical aspects, the results of free software, without getting into the philosophical underpinnings, while Free Software emphasizes the ideals, the rights and reasons for making source code available. They are two sides of the same coin--open source is largely Free software rebranded to be more palatable to the business world.
The real semantic difference we should be making is the distinction between "Free Software" and "Freeware"-- software that costs nothing but does not grant you the freedoms we all care about. Software like Internet Explorer, Adobe Acrobat Reader, Adobe Flash, Skype, and all the rest of the shareware/freeware software that to the uninformed look much the same as Free Software, but we all know they're potentially far more dangerous. I don't care if somebody calls the software we work with Free Software or Open Source, but I always correct them if they call it freeware.
Even your Debian/Firefox point confirms this--while the Mozilla license prevented Debian from making changes and still calling it Firefox, nothing prevented them from forking the codebase and releasing it as Iceweasel. This is what I see as the essence of Free--the ability to fork. Far more dangerous (and more supporting to the argument of this story) is Zimbra's license, which does not allow you to use the software if you remove the trademarked logos, but does not guarantee you can use the trademarks, either--I would argue Zimbra is not open source or Free. If Microsoft actually bought Yahoo, they could kill Zimbra, and you would not have the right to fork it.
On the patent point, for most software developers, patents are completely irrelevant. When is the last time you went to implement some feature in some software and thought "oh, I can't do that because it's patented?" Let me hazard a guess: never.
Sure, there's always the threat of patent lawsuits, but the only patent lawsuits you ever see are the ones going after the deep pockets of proprietary companies. In many ways, patents are more of a problem for proprietary companies than for Free software--we've got far more immunity because we're decentralized, nobody has a big pot of gold that makes it an attractive target for lawsuits.
As evidence, Microsoft has been sued for patent infringement several times, and lost. To my knowledge, they've never actually sued anybody for patent infringement. Sure, you hear Ballmer hollering about patents all the time, but it's a sales tactic, it's a way for them to try to persuade companies to pay extortion to them. If they ever actually launched a patent suit, it would be the best thing ever for Linux. I mean, who could they sue? Just about everybody with cash is a customer. If they started suing their customers they'd quickly become the next SCO, every corporate attorney would advise their clients to get away from Microsoft as fast as possible because it would be too much of a risk to use. And if they sued people without money, they'd lose in the court of public opinion--nobody likes a bully. And there's a small matter of the Department of Justice consent decree that would re-open and target Microsoft for anti-competitive behavior.
Sure, the patent situation is ridiculous, but it's really the threat of patents that are stifling software businesses. And this threat really has very little effect on Free Software.
Freelock Computing, http://www.freelock.com
The Open Source for Business Solutions