Be sure to read Mark Athitakis: The Way of the Litblog.  This quote is worth the price of admission:

I suspect that when somebody says that blogging had a “golden age,” the person means that there was a time (circa 2002) when it felt new and exciting, and the media wanted to do stories about it, and some people got a lot of attention really quickly (book deals! movie options!), and everybody got to have lively discussions and post pictures of puppies or argue about string theory, and it was a thrill because we all had a brand-new toy to play with and we knew who was reading us and we were finally, finally, getting some interesting e-mail. That moment has passed, so it’s easy for media folk to say blogging is old hat and move on to the new. But blogging remains a valid form, and Twitter is no replacement for it. (Twitter is more a supplemental form, I think—a supplement to a supplement.) What other online format besides blogging allows people to write at various lengths, distribute to a wide audience, and spark conversations? I suppose Facebook might qualify, but it’s a poor vehicle for lengthy, considered thought, and its system is designed to push your ideas only to your closest friends. If blogging is over, nobody’s created a suitable replacement for what blogging does.