Just discovered trac this evening and setup one instance for me to
play.
It looks pretty cool for managing projects. The timeline
feature is specially nice, as it brings wikis, checkins and bug
tracking changes all into the same place. And even better! You can
subscribe to the rss feed and read it directly from your desktop.
You can link from checkin messages to issues by using a special syntax
on the checkin message. And the killer thing is that all the
checkin message querying is done directly on the subversion repository
directly, which means it already picks your old history of checkins
and makes them searchable and browsable. No special
configuration needed. No import scripts to run. Nothing.
It also has an embedded wiki, which accepts reStructuredText, and
adds a trac:: directive to reStructuredText that allows you to
link directly to issues, files inside subversion, reports, etc.
All the data is stored using sqlite, which makes it very lightweight
and simple to configure and maintain.
I am hoping to get my sqlos wrapper working with sqlite so that it is
possible to browse the database using Zope 3 wink.
Sidnei Silva 
may find interesting
this is a very appreciated project tracking tool, it is not open source yet the framework behind it is GPLed: http://basecamphq.com/
I love tracebacks
http://awkly.org/cgi-bin/trac.cgi/timeline
Oops…
Trac detected an internal error:
database is locked
Traceback (most recent call last):
File "/usr/lib/python2.3/site-packages/trac/core.py", line 479, in cgi_start
real_cgi_start()
File "/usr/lib/python2.3/site-packages/trac/core.py", line 457, in real_cgi_start
env = open_environment()
File "/usr/lib/python2.3/site-packages/trac/core.py", line 171, in open_environment
version = env.get_version()
File "/usr/lib/python2.3/site-packages/trac/Environment.py", line 162, in get_version
cursor.execute("SELECT value FROM system WHERE name=’database_version’")
File "/usr/lib/python2.3/site-packages/sqlite/main.py", line 237, in execute
self.con._begin()
File "/usr/lib/python2.3/site-packages/sqlite/main.py", line 508, in _begin
self.db.execute("BEGIN")
OperationalError: database is locked