Herr Fuchs sends this link, to an article by the estimable John Sides of the also estimable Monkey Cage.
In one part of the article, John asks, "Should Junior Faculty Blog?" I think his answer is a bit too optimistic. If your blog is invisible, why waste time on it? And if it is successful, and you become known for it, you are taking a pretty big chance when it comes time for promotion. Either way, I'd say, "no," at least until your fifth year or so in a TT job.
On the plus side of blogging, I blushingly refer to this article on "Truthiness" and political blogging, in a special issue of PC edited by blogging stalwarts Drezner and Farrell.
(Yes, it's gated. Send me an email and I'll send you a PDF, if you don't have access through a library).
UPDATE: On some comments. if you played Russian Roulette and won, that doesn't mean that it is a good idea to play Russian Roulette. So the fact that some people start a blog early, and still get tenure, is not proof it is a good idea.
Good of Dan D to write a comment also. Now, I don't think that the blog was the reason Dan did NOT get tenure. But I (and Dan) will always wonder a little bit whether it had some negative effect.
Dan wrote about it here... Seems like a long time ago now. Dan is fine, still cute and perky. But we'll never know.