While most sys admins may complain about certain users (you know we all had those "special" users), they still had a sense of honor and duty, took ownership of the systems they managed and protected their network and data.
Snowden, on the other hand, had no honor or commitment to his employer and violated his oath. He (and Manning) will be responsible for having all sys admins painted with the brush of distrust and disloyalty. Prepare for decreasing pay levels for entry level, tougher and more complete role separation, higher skill requirements, more experience and other requirements (severe, lengthy and invasive background checks, drug tests). Employers with any kind of sensitive IP or classified information will start clamping down, if they haven't already.
If you think Manning or Snowden have done any favors to the IT community, you will be sadly mistaken. Personally, I'm embarassed that they are considered to be or called system administrators.
While there is no codified ethical standards for system administrator behavior and procedures, Stephen Northcutt published IT Ethics, which should be on the shelf of every IT sys admin.
Jayne: Testing. Testing. Captain, can you hear me?
Mal: I'm standing right here.
Jayne: You're coming through good and loud.
Mal: 'Cause I'm standing right here.