Unlike a traditional conference, an “unconference is a participant-driven meeting”. Preparing for it sounds heavy perhaps getting to understand the concept is a better way to describe it. But none the less, this great guide will give you a lot more details on how to prepare to attend an unconference (pdf). But in short, going to an unconference is like going to a conference, democratised - that means you are the speaker (as well as the audience)! But wait a minute, you did not think it’s all just powerpoint in a lecture hall, did you? But equally, don't be shy, if you are not up for being the only speaker in the room, you can always start and discussion and get everyone exchanging ideas (and here is some useful guideline on etiquette). The format, length, topic of session can vary a great deal and here are some examples for inspiration:
60 seconds to land
Round table/forum discussion
Spread the word, spread the love!