Well, I don't think it's a question of whether salaries should be kept secret or not, I think it's a question of whether one should access data he's not supposed to just because he can.
I find it interesting that this is getting down-modded.
I think the ethics of IT is an interesting and important subject, and I was surprised to see someone unabashedly admitting to using his position to read confidential material.
I don't think our industry has a good enough set of accepted ethical guidelines, and I'd like to see that change.