We certainly don't recommend using Windows as a web server, but some organizations just don't have any other option for a server environment.
In looking for a best practice for implementing Drupal 7 on IIS, we wrote up the following guide:
We don't pretend to be Windows Server Admins, but found existing guides inadequate. We would like to have more collaboration around this document, so if you are interested in contributing, please let us know.
Hopefully this is able to help more organizations adopt Drupal 7.