Windows, Mac, AND Linux

Munich's original plan was 100% migration to LiMux Linux, so they could achieve independence from the evils of proprietary software. That has turned out to be impossible. Therefore, the city of Munich will be forced to maintain not one, not two, but THREE operating systems on their desktops for many years to come:

http://futurezone.orf.at/stories/288129/

Die Migration soll bis 2012 auf 80 Prozent unserer Arbeitsplätze abgeschlossen sein. Das ist so unsere Zielgröße. Wir werden niemals Linux auf allen Arbeitsplätzen einsetzen können. Genausowenig wie wir in der Vergangenheit zu 100 Prozent Microsoft-Betriebssysteme hatten. 

Das liegt daran, dass bestimmte Fachverfahren und Arbeitsplätze Software brauchen, die es nur auf Macintosh und Windows gibt. Bei diesen Systemen wäre die Umstellung unwirtschaftlich. 

Here's a Google Translation:

The migration should be completed by 2012 to 80 percent of our jobs will be completed. That is our target. We will never Linux on all workstations can use. Just like we have in the past to 100 percent Microsoft operating systems were. 

This is because certain specialized procedures and software jobs need it only on Macintosh and Windows. With these systems, the conversion would be uneconomical.

In plain English, "We will never use Linux on all workstations", and "Certain specialized procedures and software will only run on Macintosh and Windows".

So rather than free themselves from the chains proprietary software, Munich has spent millions to become only 10% free. To make matters worse, they are going to have to maintain a three desktop operating systems for many years to come.