I tell myself that, but in truth the main value in taking notes is it forces me to pay attention. When I'm not daydreaming about how I would make the last point in a different way (thus missing the current one), or thinking about whatever project I'm doing at home I get a lot more out of the talk.

I sometimes pretend I'm translating to Spanish (I don't know near enough Spanish to do this, but in my mind it is okay to make the English words with a Spanish ending and not worry if anyone else would understand). this doesn't work as well, but it still keeps my mind on listening and so I get more out of it.