Dapper to Feisty dist upgrade 
Goes smoothly as documented here:
https://help.ubuntu.com/community/FeistyUpgradesManualGet used to the idea of running dist-upgrade more than once.
If your using trac, python-clearsilver will give you problems. Just remove python-clearsilver and python2.4-clearsilver, which will remove trac, and then reinstall trac. It will grab python-clearsilver as a dependency.
root@ztaylor:~# aptitude install trac
Reading package lists… Done
Building dependency tree
Reading state information… Done
Reading extended state information
Initializing package states… Done
Building tag database… Done
The following NEW packages will be automatically installed:
python-setuptools
The following NEW packages will be installed:
python-clearsilver python-setuptools trac
0 packages upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
Need to get 208kB/761kB of archives. After unpacking 3322kB will be used.
Do you want to continue? [Y/n/?] y
Writing extended state information… Done
Get:1
http://us.archive.ubuntu.com feisty/main python-setuptools 0.6c5-1ubuntu1 [208kB]
Fetched 208kB in 1s (207kB/s)
Selecting previously deselected package python-clearsilver.
(Reading database … 40885 files and directories currently installed.)
Unpacking python-clearsilver (from .../python-clearsilver_0.10.3-4.1_i386.deb) …
Selecting previously deselected package python-setuptools.
Unpacking python-setuptools (from .../python-setuptools_0.6c5-1ubuntu1_all.deb) …
Selecting previously deselected package trac.
Unpacking trac (from .../archives/trac_0.10.3-1_all.deb) …
Setting up python-clearsilver (0.10.3-4.1) …
Setting up python-setuptools (0.6c5-1ubuntu1) ...Setting up trac (0.10.3-1) ...