Charlie Stross has an interesting diagnostic.
We human beings are primates. We have a deeply ingrained set of cultural and interpersonal behavioural rules which we violate only at social cost. One of these rules, essential for a tribal organism, is bilaterality: loyalty is a two-way street. (Another is hierarchicality: yield to the boss.) Such rules are not iron-bound or immutable — we're not robots — but our new hive superorganism employers don't obey them instinctively, and apes and monkeys and hominids tend to revert to tit for tat quite easily when unsure of their relative status. Perceived slights result in retaliation, and blundering, human-blind organizations can slight or bruise an employee's ego without even noticing. And slighted or bruised employees who lack instinctive loyalty because the culture they come from has spent generations systematically destroying social hierarchies and undermining their sense of belonging are much more likely to start thinking the unthinkable.
Edward Snowden is 30: he was born in 1983. Generation Y started in 1980-82. I think he's a sign of things to come.
PS: Bradley Manning is 25.