Okay, after spending a fair amount of time chasing various plugins, I've settled on
to limit reading posts on the blog to those who are logged in.
Note1: I needed to post at least one entry to my "public" category to keep the one "private" post from showing up on the home page without regard to authentication.
Note2: Something's broken in the management of comments. Unless I deactivate the plugin, I don't see any info on the comment in either the Moderate or Manage Comments screen. But since I can click "edit" to see what's there, this isn't a big deal.
Other things I tried:
though it's documented to have a category access feature, I just couldn't get it to work at all. And it seemed to be more granular than I needed.
Private categories - http://dev.wp-plugins.org/browser/private-categories
that threw a php error and since it's a couple of years old I didn't spend too much time investigating.
The problem I'm trying to solve is how to make the WordPress install a private discussion with periodic postings available to the public as the discussion evolves. So I've got a special category "public," but all the other categories are protected from anonymous users and new users.
My thanks to David Coppit for the plugin.
If there are other options, I would still be interested in hearing others suggestions.