Unfortunately, this can't really be fit into the way easy_install configures its
installation directory; there can only be one target directory per program
invocation.  So we could certainly change it (in 0.7) to *always* default to the
exec-prefix directory, or add an option to do that, but there isn't any way to
do it on a per-egg basis.  (Although perhaps it could refuse to update a
platform-independent .pth to point to a platform-specific egg, without using a
different option.)

When running easy_install with a platform-dependent egg on a python installation
whose exec-prefix differs from its prefix, the egg is installed in the
platform-independent site-packages directory.  In some senses, this seems okay
because the egg name contains the platform name, but the easy_install.pth file
only includes the egg from one platform, and if multiple eggs with the same name
(but different platform) are added to the easy_install.pth file, then only the
first will be considered.

This comes up when using a common installation of python on a network share with
different exec-prefix settings for each platform.  This would not be an issue if
easy_install were to install platform-dependent eggs into the platform-specific
site-packages location and set up the easy_install.pth for that location
appropriately.

I am able to set things up this way manually, but it is not quite as "easy" to
"install."