That's the question asked by Gregory Cowles in, appropriately, a Paper Cuts blog post.
The occasion is the publication of Jose Saramago's The Notebook, a compilation of blog posts that the Nobel Prize winner wrote from September 2008 to August 2009.
Cowles' answer to the above question?
"[Saramago's blog posts are] fascinating and smart and provocative, and a lot of fun to dip into. But they strike me as too topical and too fleeting to count as literature, and they reinforce my impression... that blogs are by their nature part journalism, part journal."
So that's, uh, a no.