FWIW. I'll answer with something that isn't on any of those threads. We have, in the 10 years I have been singing with my college chorus, both as a student taking the class for credit, and as a volunteer, always been encouraged to record our rehearsals so we have something to work with at home.
This year, for the first time, we were all given a form to sign that we had (by virtue of our professor also signing it) been given permission to record the class, and that we agreed that these recordings were for our own use and we would not post them to YouTube or disseminate them publicly, in any way.
I don't know if we have new lawyers, or if there was some ruling handed down in the past year that now makes this necessary, but, apparently, that is now a campus-wide requirement. I don't remember now if the form also indicated that we were aware that others might be recording and giving our permission for that. It definitely constituted a contract between us and the professor granting permission for us to record. I haven't seen the form in any of my other classes, but I also haven't seen anyone recording them (and that's something I have seen, off and on again, in classes in the past.) Wait. One student was using her MP3 player to record the biology lectures this summer. No one knew until late in the term when she (can't remember why) indicated that she'd been doing so during class, in front of us all--students and professor. No one objected, and I didn't even hear any out of class wonderings about it on the part of anyone. I rather think I would have had there been any.
I wonder how it would apply if someone was using a SmartPen? I very much want one for my upcoming math classes, because I can see a definite use for attaching the lecture being given while explaining a formula to the notes I'm taking as I'm writing that formula down. I suppose I should ask (maybe) before I buy one. I've seen recording devices being used by students since I first started taking classes in the early '70s. (Obviously apparent in the days of cassette tapes). I've even used them. I've never heard anyone complain, nor have I seen their use shut down discussion. Of course, we have continued to become a more litigious society, even from those days, and we didn't have the Internet then to allow for easy dissemination. The technology that makes sharing such things is quite wonderful, but it also has made for complications that didn't formerly exist.
My guess? None of the students even think twice about it, although they might if it was pointed out. It never used to be pointed out, even when everyone knew that it was happening. (Hard to miss that huge tape player sitting on the desk.) The easy share does change things, perhaps. A form granting and allowing permission, while specifying how the tape can be used, is probably a good CYA, if nothing else.