I've been thinking about this quite a lot lately, and I have some advice for new bloggers: do it anonymously, at first at least.I only disagree with this latter contention. I'm personally of the opinion that anonymity (or pseudonymity) is a basic prerequisite for a lot of progressive bloggers.
There's a distinction between private/public figure which isn't always perfectly clear, but it's something that the internet totally destroys. If you write something on the internet, it's public. A big blog links to it, suddenly you go from 50 hits per day to 5000 in one day. 5 hours later, CNN puts it on their "inside the blogs" segment, and suddenly you've gone national to a non-blog reading audience who are perhaps unaware of conventions of blogging.
I think that until you blog for awhile it's hard to quite get a handle on how much you want to be public versus being private, and how easily blogging and the internet and the media can tear down that wall in a way you never expected.
I'm not saying that everyone should blog anonymously forever, but until you get a better idea of how it fits into your life, I really suggest starting out that way.
Any blogger runs the risk of having his name, identity, and location "outed", but the risk seems to be higher for progressives, considering the attitude and actions of both real Freepers and Low-Grade Freepers (LGFers, natch) towards those who disagree with them. Rare's the time you're going to see even the most enthusiastic leftie seriously threatening the lives of the opposition, but as David Neiwert has rather exhaustively demonstrated, the same is not true on the right.
At the moment, nothing truly nasty has happened to a progressive blogger, but the Internet also has a tendency to archive what you say, and one never knows what tomorrow may bring.
Without the possibility of pseudonymity, there is no privacy. Without privacy, free speech is impossible: fear will eradicate it.