On hackathons it's quite common. You leave a laptop on your workplace, go for lunch, or for a walk, or whatever. Usually there are only other hackers there, few bystanders, so the environment is quite secure.

That's why it's so sad when situations like those happen - it undermines the trust within the community. On Airport, or at the coffee place I wouldn't expect my laptop to be there if I left for an hour. On a hackathons I left my laptop for hours at a time. The only problem was that with the amount of MB Airs laying around, unless you had some stickers, it might take more than a moment to find yours :)

This attitude that "hackers" are all virtuous is a bit naive. I've known talented hackers who were not above taking advantage of another's misplaced trust. Would you leave $1000 in cash unattended on a table at a hackathon? Why would you leave your laptop?

If your observation is typical (and I will assume that it is) then if it's so common for people to leave something like that un attended then I would think there is an obligation on the part of the organizers to provide some type of security for the laptops because from what you are saying there is a defacto assumption of security by the way people seem to behave.

That could be as simple as something that would allow someone to easily lock the device to the desk and include providing the lock cable (depending on the cost).

Because from what you are saying it is not practical for a participant (and almost expected) that the laptop will be left unattended.

Edit: Defacto assumption of security or safety by virtue of the type of attendees and the venue.

You have a point, but in this case it's a hackathon with over 1000 people. It can hardly be called a "community" thing.