I have seen this discussed on a few occasions lately and even had a commenter say to me not too long ago, "Your husband must not read your blog."
So here are my blog rules that I have set for myself. I don't blog about anything regarding my husband or our relationship, our families, and so on, that I haven't said or wouldn't say to him. I follow the same rules when discussing him with friends. I have a few friends who will say something about their husbands, husband's or own family, etc. and then they say "Don't tell him that I said that" or "Don't tell him we talked about this" or they will whisper their conversation if their husband is within hearing distance. I don't do that. There isn't a whole lot I wouldn't say to my husband if I thought it or felt it. He actually appreciates the fact that I discuss some of my frustrations, issues and pissy moments regarding him, his and my family, with friends because that means I am not screaming at him about it. I assure you, though, if I am bitching to you about it, he has already gotten an earful. It's not anything cruel or vicious, it just may not be the nicest discussion in the world. But I say it, he says it and we don't need to tippy toe around each other in regards to venting to one another or to others. And that's how it ends up on my blog. If it's not MG discussed/to be discussed, you won't be reading about it here and you won't be hearing me talk about it.
As for my kids, I won't blog about anything that would be overly embarrassing to them. I won't out them on anything they wouldn't most likely share with their friends or extended family. They deserve some privacy. I will blog about silly things they say or do, which may be a LITTLE embarrassing for them, but not to the point of them crawling in a corner.
As for friends, I don't blog about them much except for fun and good things. I don't really have negative things to blog about them and if I did, I wouldn't.
As for in-laws, parents, siblings, acquaintances and people I pass on the street - that's a free for all. I (assume) they are not reading and if they are, it's not because I invited them here (with the exception of one of MG's sisters) and they will either have to deal with what they read or stop reading. If you have followed me for very long, you know I had this situation recently and changed my blog address and went somewhat incognito. I guess it worked, but I probably won't ever know for sure since when I did find out about it a couple of months ago, it was by accident. They had been reading for over a year without comments or a shout out that they stumbled upon my blog. (Although my husband is pretty sure my MIL, yes HIS mother, left the comment that led to this response.)
So those are my guidelines. What guidelines do you have, if any?