An ethical guide to blogging by upstart explained the code of ethics in the blogging enviornment.
It explains the importance of being truthful and making a clear differentiation between truth and opinion based statements. For example if the particular content is focused on rumours and gossip is must be clear to the reader.
You are unable to plagiarise when blogging, must link to relevant material, giving it credit when its due, remain transparent about personal associations of conflict of interest.
If mistakes are made, such as spelling or titles, it must be corrected immediately and not just left, as it is important to remember that the content you produce is assumed as truthful, and once posted is available for everyone on the web to see.
Encouraging audience participation and freedom of speech can create a sense of community, which is important in a ethical and just blogging environment.