I've been asked this both publicly and privately over the last month since I received the award, and I provided some information on a previous blog post Congratulations 2009 Microsoft MVP. The real answer is that there isn't a magic formula that can be followed to become a MVP in any technology, let alone SQL Server. The key requirement to becoming an MVP for any technology is a demonstrated dedication to supporting the community over the past year. How one actually goes about supporting the community differs person to person and case by case.
One thing to keep in mind is that quality is as important if not more important than quantity. Posting responses to forums questions consistently but never actually answering the question at hand doesn't support the community very much. Writing in a blog about personal information might build your blog post count, but it isn't centered towards a specific technology. Being a member of a local user group and attending meetings but never presenting or being involved is good for personal learning, but not expanding the knowledge of the community.
One of the requirements is that you have to be nominated by an existing MVP, or a staff member at Microsoft. This entails that you have or are doing something that gets noticed like answering questions efficiently and effectively online, while providing information to explain and educate the requestor as well as anyone who may find the post by searching later on. Speaking at local events and writing articles that get published in print or online are other ways to get noticed. At least for SQL Server, many of the speakers at local events are current or former, yes I said former, MVP's.
So why did I say former? The MVP award is only for one year, and if you stop contributing, you can be assured that you won't receive the award the following year. Even if you do continue to contribute, it isn't guaranteed, see statement above about no magic recipe. Each quarter the current MVP's whose award is expiring, and new candidates for MVP are reviewed by a team to determine who will receive the award.
Hopefully that answers the question for anyone who is curious, while not answering the question since there isn't a definitive answer to this question. Personally the first email I got about being nominated caught me off guard. I certainly don't count myself amongst the ranks of MVP's like Paul Randal, Kimberly Tripp, Kalen Delaney, or the long list of other subject matter experts whose work is well above anything I have done.