> 1.  [TARGETDIR] will stay on the path.  I think that is fine, since the 
> python.exe will be gone, so will never be executed.  Do you agree?

Completely disagree. Adding something to PATH is nearly unacceptable
clutter even during installation, and completely unacceptable (to me)
after uninstallation. If you install Python several times, will the path
get longer and longer?

In principal, uninstallation should completely undo installation. There
should be only plausible exceptions, e.g. when the user still has files
in a directory, deleting the directory is unacceptable as it would also
delete the files. The big problem where the Python installer (and MSI
in general) fails is uninstallation of file associations, which doesn't
restore the file assocations to what they were (of course, that software
might be gone)

> 2.  [TARGETDIR]\scripts will also stay on the path.  And it may still 
> contain scripts installed by the user or by third-party installers like 
> the SCons installer.  I don't know enough about how Python works to 
> know if that's a problem.  Is it a problem?

To me, any change to PATH is a problem... (I really think that software
installation should never ever touch it - this aspect of the operating
system completely belongs to the user resp. the system administrator)

> P.S.  Would you prefer to discuss this by something more synchronous 
> like telephone (I will pay the tolls) or instant messaging?

I don't think this can be done for 2.6, so there is no need for
synchrony - there is plenty of time to come up with a solution
for 2.7/3.1. In any case, I'll be away for the next three weeks.

> It cannot[1] remove them at uninstallation.
> ^ [1].  I have inferred this fact based on 
> http://www.isg.ee.ethz.ch/tools/realmen/det/msi.en.html -- scroll down 
> to the "Setting the PATH" section

I think this is incorrect. You cannot uninstall the path through
unsetting the PATH variable, sure. So perhaps using the Environment
table is the wrong approach in the first place. You can do nearly
anything in a custom action, so it should be possible to remove the
path entry on uninstallation by means of a custom action.

If such a solution was designed, there would still be many questions,
such as:
- what is the actual problem being solved? Is it real? Could there
  be other solutions to that problem (such as installing things into
  system32, or somewhere else that is on the PATH already)?
- if the path is modified, should the Python directory be added to
  the beginning or the end?
- IMO, this feature needs to be customizable, and IMO, it must be
  turned off by default. So how should such customization be offered?
These questions can partially be discussed in the tracker item proposing
the patch. The very end-user related aspects of it need to be discussed
on python-dev (perhaps taking a poll whether this is desirable, whether
it should be optional, and if so, what the default should be)