What he did was certainly illegal. It's highly debatable as to whether or not it was wrong.
The average american commits illegal acts daily, but I doubt you were referring to that.
If you can give me a hint as to why it might not have been illegal, I would love to be enlightened.
(Not that I'm too keen on the possibility that the U.S. government would grant him the chance of a fair trial...)
(I'm not trying to make a point about Snowden's particular case, just speaking in general.)
I do hope there's a demographic shift here. Facing heavy-handed laws regarding drugs and such, web-savvy young people seem to be slowly catching on about tactics like nullification, not talking to police, etc.