Afraid I'm not up to date on the technology, but I thought I would chip in with an observation about protocol. I don't know what other people think, but my sense is that you sometimes have to be a bit careful about recording people without their consent, or at least with the way in which you use the material you've gathered. Whilst giving a lecture or a conference paper does involve a commitment to making your ideas public and up for discussion, it's not quite the same as a book or article: people can misspeak, oral presentations don't come with explanatory footnotes, and responses to questions can be made on the spur of the moment in a way that doesn't give a full representation of the person's views. Basically, if you wanted to record speakers so that you can cite their comments in your thesis I'd try to get a printed copy of the conference paper from them, or find something in their publications to back up your idea, rather than rely only on your recording.
Maybe this is more acceptable in other disciplines though?