Our volunteers feel strongly that their efforts should be enjoyed by all, so we won't design, install or configure systems that restrict access to a subset of users. Thus, for example, none of our nodes use WEP or similar security that requires prior knowledge of a key or password to obtain access.
We take security very seriously. Both security of the building we happen to be working in, and the computer security of those who will be using the system. We work hard to educate node users on the best practices to keep their computer safe from others and to keep their information private from others.
A more subtle example of how 'provide access to all' works is our relationship with landlords. We are happy to help a landlord add wireless access for their tenants, often saving them thousands of dollars in the process, but in return we expect a good faith effort to provide wireless access to surrounding buildings. Thus, we will typically require a rooftop antenna and possibly a relay link, even though inside equipment may service the majority of tenants.