Understanding the time span in which these artifacts (for a supposed conference) ought to be made/used is an interesting way to to approach necessities. It's easy to get caught up in the conference alone, but much of what goes into a great production is its pre-production. As far as practical, poetic, or persuasive, this is also something I've never thought to identify off-the-bat. These three "p"s pretty much sum up how the design should speak, and these appeals can change as time goes on: posters may need to be persuasive in the beginning but very much practical during, and maybe more poetic afterwards (?), I don't know.
Thinking about themes, and considering the guest speaker, these titles came to mind:
Modularity: Facilitating Humanity
Irrational Order (oxymoron?)
Natural Processes & Modularity
The Human Grid
Interactivity in Modularity