Given the numbers of people coming to Rails Camp, it's recommended that you organise buses to get everyone to and from the venue. You should definitely have a bus (or two, depending on numbers) departing from the closest airport, and potentially a stop in your city's CBD - especially if there are a decent number of local Rubyists who might like that transport option.
Asking which stop people prefer (in both directions) when they purchase their tickets is wise, because it may work out better to have separate buses travelling to/from the CBD and to/from the airport.
As discussed in the catering section, it's probably wise to add a stop at a shopping centre between the CBD and venue on the Friday, for attendees to buy their own snacks and alcoholic beverages.
Having the aforementioned bus plans figured out - once you've spoken to a likely bus company and figured out the best time for people to arrive at the camp - means you can let everyone know what times the buses depart from the airport/CBD, and then they can book their flights. Hence, these details are good to have locked down at the same time as you put tickets on sale, so flights can be organised well in advance.
You or other organisers should have a car or two available during the event for any emergencies, or to go get extra supplies should you run out of something.
There's a decent chance some attendees will drive as well, and they are often happy to help out with lifts and errands.