I see everyone is missing the point of the GPL.

Go read up on *why* RMS created the GPL.

If I as a customer have a choice between a product
that provides documentation and source code vs
a product that does not provide documentation and
source code, guess which product I am going to buy?

The reason to use NetBSD (or any *BSD) in a product
instead of Linux isn't the BSD license vs the GPL,
it is because *BSD is a better version of Unix
than Linux.  The BSD license may allow you to
keep your sources closed, but that is just going
to lose you customers.

If you haven't noticed, there are a lot of commercial
products out there based on Linux, dispite the alleged
disadvantages of the GPL.  They list the source code
availability as a feature.  It is a selling point.

The next time someone decides to do yet another fork of BSD,
(as if 4 weren't 3 too many) they should make it GPLBSD.