Along with Ed Winkleman, and with a nod back to my AiA blog roundtable rant, I'd recommend Sarah Boxer's article on blogs in the latest NY Review of Books.
Boxer summarises the creation and rise of the blog, the nature of the 'blogosphere' and some of the characteristics of the bloging medium and mentality. Upside - a great overview, and some of the best writing I've read on what makes blogging distinct from other forms of communication.
Downside - a stronger emphasis than I'd put on the fame-seeking side of blogging (as opposed to community-building) and, inevitably, being adapted from the print original, no links to the many blogs and blogging moments she mentions. Which underlines the whole point, really.