Steps to reproduce:

1. python-2.7.2.msi /qb
2. Check registry for HKLM\SOFTWARE\Python or HKLM\SOFTWARE\Wow6432Node\Python

Expected behavior:
The key will exist and contain a key for 2.7 providing information such as the installation path.

Observed behavior:
The key and its subkeys are not created at all.

Workaround:
Don't use the /passive, /quiet, or /qX options. 

Additional information:
* Running msiexec /fm python-2.7.2.msi does not insert the missing registry entries.
* Running python-2.7.2.msi without options after install and choosing repair /also/ fails to insert the missing registry entries.
* Aside from inserting the entries by hand, uninstalling and re-installing with the interactive GUI seems to be the only way to populate them.

I've tested this on 64bit Windows 7 with 32bit Python 2.7.2 msi package only.