Conferences are a roiling storm of egos. This is where science really happens. One of the most important lessons an academic can learn is that if they have a fantastic result, it is not enough to publish it in a paper. No-one reads papers. The paper only exists as proof that you got the result before someone else. No-one will know about your result just because you published a paper. They won't even know about it if you go to a conference and deliver a talk; no-one listens to talks. Only if you also individually corner every relevant researcher you can think of, and forcefully lecture them about your result during the coffee breaks, lunch, dinner, drinking at the pub, stumbling home from the pub, or even, and perhaps best of all, bleary-eyed over the hotel breakfast the next morning -- only if you do all of these things, will there be a small chance that not everyone will be ignorant of your result.
For those who remain ignorant, the next conference is the place to set them straight. If you are an especially brave young researcher desperate to become known, then you can force yourself to listen to their talks, and then interrupt with a mock-polite question that causes everyone else in the audience to wake up and understand the question as a statement: "I've done that already." Among senior scientists, such questions are reserved either for only the most bitter rivals, or are asked only by complete jerks with no sense of propriety who worship the sound of their own voices. But such deplorable characters are extremely rare, and make up only 73% of successful scientists.
No, the professional way to correct a colleague's misunderstanding of your results, is to have a quiet chat with them in private during a coffee break. "Private" may well mean surrounded by a small circle of their students, postdocs, and collaborators, and some tact will be required. The best technique is to act like you're interested in their work. "Oh, really? That's very impressive. Tell me more." Then slip in comments like, "I was working on something similar myself a few years ago, and your work puts it in an interesting new light." Your interlocutor, if they are also a professional, will understand what's going on or, at the very least, understand that a few polite questions about your work is the only way you'll give them a chance to blather on some more about their own. If you've done it right, the whole exchange will appear from the outside as a polite and open intellectual discussion between dedicated scholars.
In reality there are no open discussions at conferences. The phrase, "Let's think only of the science, and talk openly," is certainly very welcome, but only because it translates as, "I've run out of ideas, can I steal some of yours'?" There is no sweeter music to the professional scientist's ears. A truly open discussion amongst a large group of scientists is a sure sign that their field has reached a dead end. Some conference organisers will naively include a "discussion session" in the programme, perhaps because the act of conference organising has triggered a distant memory of the pure ideals of science, but more likely because six months devoted to conference organisation has left them in need of a few research ideas themselves. "If we're going to go through the trauma of conference organisation, don't we deserve a few free projects out of it?"
The surest sign of a field at its most active is a formal discussion session in which no-one offers a single view. A senior figure lists all of the most obvious pressing problems that everyone knows about already, and solicits answers. Several equally senior and equally out-of-touch professors will pontificate at length on their past successes in solving entirely different problems. Everyone else will sit there with smiles on their faces, and if called on to offer suggestions to solve the Ten Greatest Problems Facing Us, will reply, "Nope, sorry, nothing here."
Beyond these "professional" issues, conferences are great fun for everyone, although somewhat gruelling. Once upon a time a student could party all night, and then during the day they were provided with long sessions of vacuous talks to sleep through. Now they substitute the sleep for Facebook, which, besides the proliferation of embarrassing drunken photos, leads to dangerous levels of exhaustion by the end of the conference. Considerate conference organisers will disable the wi-fi network in the auditorium to guarantee an essential student recovery environment. Unfortunately, though, most organisers cater to the professors, who only stay out at night long enough to cackle over a few reminiscences of their own student conference experiences, before heading back to their hotel rooms to maliciously email last-minute talk-presentation suggestions to their students. For the conference sessions proper, the professors are awake and engaged in important work on their laptops, and also Candy Crush.
If you are wondering if anyone is listening to the speakers themselves, never fear. The speakers are listening to themselves, and nothing could make them happier. They are contentedly mumbling away to themselves down at the front of the lecture theatre, which is not so much a stage as a place of egotistical seclusion, a tranquil valley for the mind. On one side of the valley a massive screen displays the incomprehensible slides they jumbled together during the previous talk. On the other is a comforting hillside of laptop lids. In another life, they might have been tempted to whip out their easel and paint it. They don't mind that no-one is listening. It is enough that a jealous competitor will try to ask a difficult question, a desperate postdoc near the end of their current employment contract will suck up to them afterwards, and the odd dorky (or dorky odd) student will take notes.