Don't believe in the SaaS (Software as a Service) model?
Check this out... Microsoft is rolling out their hosted version in Sweden starting on the 19th March.

The solution includes:

Exchange Online (read Outlook)
Sharepoint Online
Live Meeting
Office communication

Read more at Microsoft (Swedish, English).
One of their first clients in Sweden is one of the largest hotel chains in the Nordic countries, Scandic (IDG article in Swedish).

My thoughts
I believe that the majority of small and medium sized business will use hosted versions of tools for mail, communication suites, wikis and so on. The fact that Microsoft is moving in here will make this transition faster than ever.

Still don't believe in the SaaS model?