Inside Higher Ed has an article about tweeting at conferences, which apparently has a lot of people up in arms. The thrust of the argument is in fact rather sad, since it revolves around fear of having one's ideas disseminated. My feeling is that if you are very concerned about having your ideas stolen or somehow misrepresented, then don't present at a conference in the first place. In general, everyone should be really happy that their ideas are being discussed publicly at all. That should be a good thing!
There was also this argument:
Where some of her peers consider Twitter a constructive tool for batting around ideas, Nopper says she believes that the main reason scholars tweet sessions has more to do with personal branding at a time when many academics are scrambling to be noticed. "Along with it simply being distracting to some presenters, we need to consider how live-tweeting at conferences is a form of neoliberalism, with scholars employing social media to increase name recognition in and outside of the academy in hopes of getting more paid opportunities," she wrote.
I don't know anyone who makes money by live-tweeting at a conference, and I can't imagine how one would go about doing so. Corporations do not have their employees covering the hashtags of academic conferences to send out cash.
In any event, having your ideas and your name disseminated is good for you. Being noticed--whether you are the presenter or the tweeter--should not be viewed in a negative light.