People that usually go at home around 5:15 but some times are there longer because they want to finish something they are doing. Or sometimes they go out at 4:58 because they have a non programmimng related date.
People that when are not at their job want to go out with their friends, watch tv, be with their family and not think about programming or see a computer for a full night, even a full week-end, but have spent more than once a full week-end experimenting with that new SDK.
People that love programming but want to take a break every now and then.
People that like to go out at their local bar and have a drink with their (non tech/geek) friends and watch a sport match. Only to meet another tech/geek guy they didn't know and end up talking about how they both hate that programming language all night.
Yes, I'll call this the 515 Manifesto.