No free lunch
Cnet references some research from the Yankee group that says that moving to Linux might not save money for many companies.
Duh. Any change in working systems is going to be expensive even if the OS is "free". That is why, until there is an event that pushes companies off of their existing systems, they will stay with what they have - UNIX and Windows. If Linux proves to be better than these systems over time, then the event might just be that the critical mass of application availability moves to Linux from where it is now.