Andrew Bartlett is a senator in Australia. He has a weblog. He's giving a talk about the impact of weblogs on politics and politicians, and usefully distinguishes "real" weblogs from various kinds of simulated weblogs.
Weblogs are meant to be personal. The 'campaign diaries' so many politicians are publishing are lame.
One of his main points is the importance of not breaking the political blogosphere into separate left-wing and right-wing domains -- subsets that tend to agree and reinforce each other. This may be increasingly difficult in the US, in which polarization seems to be approaching a level of bitterness not seen since Reconstruction.