Earlier quoted context omitted.
> actively pointing out to people (as Mr. Hermoso did to me) that no you can't link Octave to Mathematica because Octave is GPL (which is just a hindrance for my research, as well as to others) What exactly did you want to do? GPLv3 (which is the license Octave uses) does not always prohibit linking GPLv3 code with proprietary code. In particular, if you want to hack up a private copy of Octave for your own use, and…
We were considering making http://matlink.org/ compatible with Octave. The feedback I got on this was part of why this wasn't done. To make MATLink user friendly, it needs to come with compiled binaries, which would be linked against Mathematica's closed source MathLink library. If it is the case that GPL doesn't forbid this, I'd love to hear about it.
The only caveat would be if your job is at a university, and you plan to give copies to students. Distribution would be legally impossible.