I have been following the case of Byron Sonne as best I can, the case is under a media ban so it is not easy. That said I think it is worth being aware of even if you are not into security.
Essentially sounds like he was a white hat hacker that probed the G20 security and posted about it openly. Also sounds like the prosecution is trying to use him to justify the G20 security spending. The whole tale sounds very sad, and like a huge misunderstanding between the hackers curiosity and the prosecutions/governments/police opinion of him. At this point almost all of the charges have now been dropped (9months after he was arrested) only an explosives charge and "counseling the commission of an indictable offence" remain.
Here are a few links if you want to know more:
http://podcasts.tvo.org/searchengine/au ... 77_48k.mp3