I link today to a post from Dan Power of Hub Solution Designs:
Building a Data Governance Organization
Dan has it right – you should look at Governance as the foundation of an MDM initiative, and it’s a program (multi-year) instead of a project (shorter term). I hadn’t heard of his “rule of thumb” on the number of data stewards required in an organization – hopefully he’ll let me use that 
I’d like to expand a little on point 1 of his argument -
Several times, I’ve seen data governance teams and MDM initiatives that never thought beyond their first year’s funding, and who were surprised when funding for Year 2 and beyond wasn’t forthcoming.
The successful Data Governance program implementer will realize that a Governance initiative doesn’t rate highly at all on the scale of initiatives that resonate with business executives because there is very little evidence of tangible benefit in the short term. However, we practitioners know that a well-implemented Governance program is necessary for the long-term health of the organization.
That’s why I like to think of these programs in terms of a physical fitness regimen – it’s not a lot of fun, but you need to do it to facilitate the rest of your life. Therefore, we need to find ways to make the exercise (pardon the pun) more fun and necessary, much the same way that trainers find innovative ways to make our fitness programs seem less like work.
Now, back on the treadmill!