Edit: Unfortunately, the images originally included in this post are gone, because of hosting problems in late 2009. My apologies.
I found a little bug the other day, in the blubuntu-look package. It applies the Tango icon theme but doesn’t draw it as a dependency, which means the desktop icons and so forth remain Human or revert to Gnome, depending. Here’s a screenshot of a fresh 32-bit Ubuntu 7.10 installation that has the Tango set tagged, but not installed.
Oh joy, I get to report bug! :D