I am definitely more blunt in my blog, partly because people choose to read it, so they can choose not to. Still, I don't have the same level of openness in my blog as I have with close friends.
I have often chatted to my 'blogging buddy' +Stuart Torr about starting a private blog. This would be one where we could invite people and thus be more open in what we say. It felt like a lot of hard work and having previously attempted one in a work environment, it was quite cumbersome.
Facebook doesn't allow you the option of joining specific conversations (yet). Although in theory people can selectively choose who reads status updates, they are generally broadcast to all your contacts. This turns us into something similar to the original TV. One channel. On or off. Broadcasting noise.
This means that you get all a friends news without the context of offline conversations. If I know you, I know the areas of mutual interest and normally I know the areas I should avoid (or discover them along the way). Facebook currently just does broadcasts. I can't choose to hear all of a friends news - but not when they starting going on about , or see all their photos, but not photos including . Sensitivity, tact, context, permission etc. go out the window.
Google+ is taking off, and has a 'community' option which is a little like Whatsapp where you can start a conversation with specific people. This is like new TV channels being opened up. Slowly but surely we can get the choice of which conversations to join again.