[larrys]

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.