How many bloggers are really doing anything more?

At a symposium on e-literature that I went to earlier this week, Professor Joseph Tabbi, an expert on 'the effects of new technologies on contemporary fiction', as his bio puts it, made the observation that critical and reflective work wasn't happening in blogs, and while I must say that I've noticed this is often true -- how many bloggers are really doing anything more than operating a more dreamy, expansive version of Twitter, working (sometimes extremely hard) in their own newsagency-cum-corner-of-the-loungeroom-or-café to distribute or just describe chunks of sounds, words or images that someone else has made? -- I would like to think that the blog can do more than this. If it likes.