The CIPR has published its terms of conduct for blogging www.cipr.co.uk/socialmedia. All very good guidelines but interestingly the CIPR hasn't brought the guidelines into the Code of Conduct to which all members must understand and adhere to. Their reason for this says the CIPR's Francis Ingham is "owing to the fluidity of social media the guidelines will sit seperately from the Code of Conduct so that they can easily be updated to take into account new and emerging issues."
When you take a close look at the guidelines, I rather suspect that they haven't been included in the Code because they are pretty much unenforceable. I'll give you an example. Considerable emphasis is given to AstroTurfing - where PRs will use social media to fake grassroots support, hence the term AstroTurf (artificial grass). The CIPR advises PROs to act transparently, honestly and with accuracy, and never knowingly mislead.
I may be sticking my head above the parapet here but we all know that there are dedicated teams who are actively seeding blogs. The internet gives people the ability to remain relatively anonymous or even create multiple identities. Frankly it is a fact of life that any media, even social media, can be manipulated in this way. Remember the phrase 'Don't believe everything you read in the papers' - well I am afraid the same can be said for social media.