The basic idea is to present your research to a scientifically literate non-specialist audience in three minutes or less, using at most one slide.
This is an excellent way to hone your "elevator speech", which is useful in job interviews and outreach, and it can help you remind yourself why what you do is so cool.
If you're more into financial incentives, be advised that there will be cash (or nearly cash) prizes for the best presentations. This year we’re going to run separate categories for students (graduate and co-op) and post-docs, so your chances to win are even better.
If you are interested in presenting a talk, please reply to firstname.lastname@example.org. It’s helpful if you can identify yourself as a student or post-doc, but no need to know exactly what you’ll talk about yet.