As reported in the printed edition of Solothurner Zeitung next year the Swiss Canton of Solothurn will abort its Linux migration project and equip all its desktop computers with Windows 7. The Scalix web mail client will be replaced by Outlook.
The principal problem reported was that employees which were used to work with other non-free apps did not adapt well to the new environment. They complained that they could not open some documents received by mail.
What I read was a very small minority of employees sabotaged the transition and they got media on their side. There also was a proprietary database program that was very windows only widely used.
By other accounts, it was a poorly planned and executed migration, with little change management. The biggest issue will be integration between desktop applications and line of Microsoft-centric business systems like financials, document and records management, etc. There are plenty of other examples of successful MS - Linux migration projects, like Munich. Migration is a journey.