There are different modes of conference blogging:
Objectives:
Conference objectives for sponsors and participants
Transcription:
Word-for-word
Interviews:
Podcast or written word interviews of key people
Commentary:
Paraphrase with opinion
Blog real time, interspersing the opinions or views of the blogger
Perhaps the most value added activity of one person
Reflection:
Pure commentary
How most people blog conferences
Listen, reflect and post
What drives the post is usually a key quote or a contrary opinion.
Coverage:
Journalistic summaries
Background:
Provide information and links
Group Voice:
For each session, augmented by an Eventspace or Wiki, people take different notes in different forms as blog posts
Survey:
Ask a core group of questions to participants
Pictures:
Digital shots of the show
Links:
Linking to other blogs and media
Engage in conversations