This article from The Scientists provoked a number of science bloggers to write about the role of blogging in science, the role of scientists in the blogosphere, and the pros and cons of blogging for one's scientific career. See, fo example posts by GrrlScientist of Living The Scientific Life, Chad Orzel of Uncertain Principles and Derek Lowe of In The Pipeline.
They, rightly, emphasize the role of science blogs in popularizing science, demonstrating to lay people that science is fun, and, of course, fighting against all kinds of pseudoscientific ideas.
I have, before, tried to take a longer look into a farther future, and looked more at the role blogs will have in the way scientists communicate with each other and how that may affect publishing, as well as equalize the playing field, to some extent, between scientists working in various countries around the world, be it in the First, Second or Third World. Check it out here.