As for the chosen time period, it's really very simple. We had limited time, and English-language Wikipedia has year pages going back as far as 500BC. Before that, years are grouped into decades and centuries - it would have been possible to parse those too, but hey, limited time.
I noticed Leeds Hack solve this by the judges going around all the teams in the morning and having a friendly chat about the hacks being made. Gives them a chance to better understand the hacks as hackers aren't always good presenters and they get to directly ask "Which bits of this did you write today?".
Can't say I've had this problem at any of the UK hackdays I frequently attend, only the US ones I've been to.
I think one of the differences is having an overnight. The networkers and loiterers bugger off after a few hours leaving just the developers and designers overnight who want to actually make interesting things.
