You see, as much as we like to focus on the platforms, data management — the tactics around defining and maintaining business rules, definitions and access to data — is the real hard part. Best-practice companies have learned that centralizing data management as an enterprise service is not only the most efficient way to support MDM, but a whole range of enterprise initiatives.
As for master data, it really does depend on whether you're using registry-style MDM to quickly match and link data across source systems, or a persistent approach that stores the data in a centralized hub. Each has its advantages and disadvantages. To understand which is best for your company — registry, persistent, or a hybrid of each — see my prior Q/A on MDM functional requirements .