I was doing some testing tonight just to see how "hidden" one can get. I was on an alt, not my main handle. A friend on another character, who shares a global channel, helped with the investigation.
/hide does what it is supposed to.
/ghide hides you from the global friends, etc.
However it doesn't take your handle off of the channel "members list" that you can open from the chat panel. So, you are still visible to members that you share a global channel with. Not sure if it is supposed to work that way. I'd prefer it didn't.
Thoughts?