MySQL AB has an interesting article about their business model, centered around a dual licensing scheme (emphasis is mine):
Our dual licensing is an open scheme where you, the user or customer, is in the driver's seat. You decide which license is best for you, and you are free to switch from one to the other and to mix the two models. If vendor accountability is important to you, you are likely to become a commercial customer of ours. If free software is important to you, and you are happy to follow the terms of the GPL, then you are likely to become a user of MySQL under the GPL license. Technically, you will get the same software in both cases. It is only the legal implications and the assurance of service that differ.
So if you are technically competent and not surrounded by lawyers, la vie est belle.
MySQL AB calls this a quid pro quo:
Here is the quid pro quo of it. Thanks to our commercial customers, we can afford to develop and improve the product at a fast pace. That means better software and more software for the free software community. And thanks to the huge user community, MySQL undergoes rigorous "battle-testing". We deliver more than 35,000 new product copies to our user community every single day. They are some of the smartest developers around, and they make the MySQL software do tricks others didn't think of. As a result, bugs are fixed and improvements made at a very rapid pace. Consequently, our commercial customers get a highly reliable product where most bugs have already been found and fixed. At the end of the day, all groups involved get back more than they put in, i.e. a fair exchange of value.
It sounds to me that symbiosis is a much better term for describing this exchange.
Some other similar (although not necessarily identical) symbioses:
- PostgreSQL Inc. with PostgreSQL
- JBoss Group with JBoss (you may want to read White (PDF), an article about professional open source by Marc Fleury, founder and CEO of JBoss)
- Zend with PHP
- Zope Corporation with Zope
- Covalent with Apache (plus Tomcat and JBoss, recently)
- Six Apart with Movable Type (note that while MT is neither open source, only as far as one can see and hack the code, nor free software, it benefits from a similar symbiosis with its users community)
I have the intuition that not only is this model sustainable, it will snowball for a cultural reason: the "nobody got fired for choosing Microsoft"-type of IT managers (who replaced their "nobody got fired for choosing IBM" ancestors) is fading.
On a side note, this approach makes me think of Dave Pollard's model of New Collaborative Enterprises (look at the second figure titled "3. A World of Ends").