It looks like system-cleaner will be in Ubuntu 8.10, also known as the intrepid ibex.

system-cleaner is a program I wrote for Ubuntu to remove cruft from systems, and to tweak configuration files and otherwise freshen up a system so that it is similar to a newly installed system. The installer will do things like put modern mount options in fstab. Someone upgrading from an old version won't get that. They might also have a bunch of obsolete packages installed. system-cleaner provides a way to fix those things easily.

The spec may be interesting if you want more information. You may also want to look at the cruft package in Debian, for comparison.

Once Debian lenny is released, I do intend to upload system-clenaer to Debian as well.