I guess I've never really kept a change log for any project I've done. I try to keep good svn log messages, and paste-checkins will let you track that. Once there are releases I want to keep a news file for significant API changes (which is generally much easier to track than a change log). The bug tracker should keep track of some other details. I'm not sure exactly where a change log fits into that.
Oh, I wasn't aware of that one. Maybe it could be possible to pipe the check-in messages into a ChangeLog style file so those check-in messages can be read without svn or an avaliable connection... Maybe I'm too lazy, or too used to a way of doing things, but I track quite a bunch of projects and I use to read the ChangeLogs to see what has been going on and when something appealing catches my attention I give it a closer look. I just thought that would make some people track Paste more closely... and it deserves it :)
I should create an RSS feed from it using this: http://svn.pythonfr.org/public/pythonfr/utils/subversion/subverssed.py
Otherwise svn log can show you cumulative log messages.