My guidelines are a little fluid. I think I usually include my opponent's name, but I've considered withholding it, or asking them if they're ok with me posting. I think I've never asked, because then you're really asking them to dwell a little bit longer on whatever game this is - and let's face it they probably made some mistakes leading to a win or draw on your part.
On the other side of things, I've had some of my opponents ask me if I'm ok with them posting their win over me. I'm ok with it. The games are public anyways, and knowledge sharing is a good thing.
What I would be against, on principle, is posting along with the games what the person said to you during the game, without their permission.
EDIT: Regarding the permission/notification line of thinking, I think this is one of those things where you can ask for permission and expect to get it. Like when a Boss says "do you mind working on this thing" - she's not really asking, but she's being polite about how she's wording "do this".
Philidor_position, I still find it intrusive. For example: The argument stating something like,'Well it is an honor, or the masters have their games published'. I would simply say they are payed to play, and the honor is assumptive. Those who state that it is professional to report all the facts, I would say that sources are asked if their names may be used. Serious players may seriously want to remain anonymous. Professional players reap reward from publication. I would say that the majority opinion, does not necessarily lead to a thoughtful response. I do question your desire to make public the opponent in private games. What is the need or want of it? How does it matter?
OK, I'll try to explain.
the reason I like to include my opponents' nicknames (note that not names, but just the handles on their public profile) is because I like writing about the tournament situation, or how beating or drawing or losing against that particular opponent was important for me etc. If you have to be careful about keeping their name secret, than you wouldn't have any chance of talking about things such as:
"this was against my main rival in this round, who has beaten such and such players with style and showed such and such bla bla, claiming the X spot on the tournament table. Now all I had to do was beat YY, and draw against ZZ in a slighlty worse ending to face this BB in a 'tournament final' type of game." etc. You get the idea. I want to keep things interesting, I like sharing the personal atmosphere the game was played in.
Asking everyone for their permission isn't the end of the world of course, but sometimes there's the language barrier, there's the possibility of finding out you're facing a complete jerk, or some won't respond when you ask and then come grumble about it after you post it etc.
I just want to know if it's ok to not get into that.