> 2. For companies with proprietary software that doesn't sell well as
> shrink-wrap, it is an opportunity A) to reap the benefit of the unpaid labor
> of those in [1], and B) to generate revenue through support services,
> because they are the only real experts with a particular package.
> 

Another point is that some companies are coming out the wood-work to
develop tools and applications that are used by Linux advocates. This
can involve selling their application (as long as it sits atop Open
Source Software, but does not make use of Open Source code) and in some
instances, offering it in a commercial license or in a GPL license.
Troll Tech is a perfect example...QT/Embedded is now GPL free, though it
is offered at a commercial price. 

Now developers can make use of the stable existing infrastructure of
code out there (Linux kernel, GNU OS, QT/Embedded) to quickly develop
their application just as cheaply as their "microsoft" counter-parts.