Scoble has posted his Corporate Weblog Manifesto. It may seem like it goes without saying, but my experience is that it is almost always worth saying: Rule 0: Don’t do it if you don’t mean it.
There are always going to be reasons not to post. Someone in marketing will be bent out of shape. Someone in sales will be blaming you for a lost deal. The alligators will be up to your armpits. But you still need to soldier on. Several items of the Manifesto address the need to be fast. You need to make it a priority.