[lug] Blog Software?

[David Morris]

I'm looking for suggestions on linux blog software which can
meet the following requirements:

- Runs on Linux (duh) through an Apache2 web server
- Posts can be tagged with a group (e.g. Programming,
  Photography, etc.)
- Posts can be sorted by group.
- Posts can be sorted by time in either direction.
- Posts can be tagged as only viewable by certain users.
- Users can only make comments if registered.
- User registration is accomplished by a simple form where
  an email address and alias are entered and a password
  is emailed to that address.  All other details are
  optional.  Password recovery based on the same mechanism.
- Back-end script-able storage mechanism.  Specifically, I
  need to be able to create a Python application which will
  create posts from a cron job.

Those are my absolute requirements, everything else is
optional.  I'm hoping something that fits the bill already
exists so that I don't have to write my own.

Any suggestions?

--David