Robert Darnton has an interesting piece about blogging avant le lettre at the NYRBlog. Here's just a teaser:
"The anecdotes constituted the early-modern equivalent of a blogosphere, one laced with explosives; for on the eve of the Revolution, French readers were consuming as much smut about the private lives of the great as they were reading treatises about the abuse of power. In fact, the anecdotes and the political discourse reinforced each other. I would therefore argue that the early-modern blog played an important part in the collapse of the Old Regime and in the politics of the French Revolution."
However, I don't think contemporary blogging about celebrities and political hacks has any revolutionary value. In fact, I think it is exactly the opposite.