Over the last little while, there has been a conscious motion of the Python community away from "setuptools" to "distribute." The upshot of this is that distribute is maintained by a larger body of people and is much more active. Additionally, many of the bugs of setuptools have been fixed. ( The homepage is here: http://packages.python.org/distribute/index.html )
Setuptools provides a couple things: mainly, and most visibly, it's the source of 'easy_install' and 'ez_setup.py', both of which are installed by yt and by the yt install script. I've committed a change to trunk that will, instead, install the distribute packages. This should be a drop in replacement and re-running the install script should update everything correctly. easy_install will still be provided, but from distribute instead of setuptools. Additionally, I've added 'pip', which is a newer piece of software that does the same thing 'easy_install' does. "pip install" is more reliable and less opaque than "easy_install."
Anyway, I wanted to give you all a heads up. If you run into problems with anything following this change, please let me know!
With distribute, I'm going to be adding an "instinfo" command to the "yt" script, which will hopefully help with getting information about the current installation and so on. This should alleviate some of the problems of figuring out where things are installed, etc etc, and maybe even add an auto-update command.