Dave Winer's catch of the day is Diego Doval's comprehensive introduction to weblogging. The post does a great job of bringing together a his own thoughts ( checkout 'Is blogging dangerous?' answer 'Yes. Most definitely. And addictive, too. :-)') as well as a huge list of links to other people's work explaining the concepts and utilities of trackback, comments, etc.
I did notice that he doesn't include a reference to the Python Communinity Server and Python Desktop Server / bzero combination. They are not nearly as popular as blogger.com, but should perhaps be included as an option when discussions Radio Userland.
Check back as he has indicated he might add some comments on syndication to round it out. This is going to be the my standard answer to 'what is this weblogging all about?' ... go read Diego ...