Well, I've done a little digging, and I found this gem from the
wikipedia article on MP3:
http://en.wikipedia.org/wiki/MP3
It's not necessarily definitive, but let's start somewhere.
"Additionally, patent holders declined to enforce license fees on open
source decoders, allowing many free MP3 decoders to develop.
Furthermore, while attempts have been made to discourage distribution
of encoder binaries, Thomson has stated that individuals using free
MP3 encoders are not required to pay fees. Thus while patent fees have
been an issue for companies attempting to use MP3, they have not
meaningfully impacted users, allowing the format to grow in
popularity."
So basically, were gNS to include a free MP3 encoder, there's no
licensing fee...but if any encoder/decoder is included, charging a fee
might be difficult for anyone downstream. I'm not sure which
definition of free Thomson used. I doubt it's the one we're
accustomed to (Free as in Speech).