Conversations in poster sessions in academic events, referred to as poster conversations, pose interesting and challenging topics on multi-modal analysis of multi-party dialogue. This article gives an overview of our project on multi-modal sensing, analysis and "understanding" of poster conversations. We focus on the audience's feedback behaviors such as non-lexical backchannels (reactive tokens) and noddings as well as joint eye-gaze events by the presenter and the audience. We investigate whether we can predict when and who will ask what kind of questions, and also interest level of the audience. Based on these analyses, we design a smart posterboard which can sense human behaviors and annotate interactions and interest level during poster sessions.