Every company is different, so it makes sense that no company is alike in their staffing requirements to manage their Salesforce.com org.
However there is a "Standard" set of roles that a company must have to make Salesforce.com the roaring success it should be and is for companies that have these roles.
All successful Salesforce orgs have these roles:
Must be strong advocates of Salesforce.com though a complete understanding o the system itself.
Must be coached in handling management requests to make unauthorised system changes. (What I call "if daddy says no then I'll ask mummy")
Project Management Lead
Technical Development Lead
Business Analyst Lead
Data Steward Lead