Various colleagues and readers have asked why I'm not participating in this conference at HLS. Paul Caron kindly invited me, and while I thought at first I'd do it, I decided in the end that I was too busy and that I didn't really want to attend a conference on what strikes me as a topic of no intellectual interest. My colleague Kate Litvak says the sensible things here about blogging and scholarship, to which one might only add (as Kate and Larry Solum have noted) that blogs are useful for getting actual scholarship into circulation (think of Caron's tax blog or Solum's Legal Theory Blog), often via links to SSRN. The other main limitation of blogs as forums for serious scholarly debate--tactfully not noted by Kate--is that only a miniscule number of first-rate legal scholars in any field actually blog on scholarly topics; indeed, if you subtract the Chicago faculty blog and Balkinization, "miniscule" may overstate the number of leading lights in their fields who blog in their areas of scholarly expertise (you can probably count the remainder on one hand). I find it hard to see how blogs can have much significant scholarly impact when the most significant scholars rarely participate in the forum, or, at least, rarely participate for scholarly purposes.
Blogs are great for circulating information of professional interest (Solum's Legal Theory Blog is the model on that score), for discussion of intellectually superficial topics like politics and current events, as well as for ranting and venting. Their impact on scholarship is minimal, at best, which is probably a good thing.
UPDATE: Here's two cases in which scholarly expertise was brought to bear on matters of political importance--so cases somewhere inbetween the blogging purposes considered above, and cases which certainly bring credit to the medium: Michael Froomkin (Miami) on the torture memos (one instance here) and Eric Muller (North Carolina) on crytpo-fascist Michelle Malkin's whitewash of Japanese internment. First-rate stuff that anyone would have been proud to have written, and the Internet certainly made it possible for this well-informed, scholarly work to reach a relatively wide audience quickly.