I don't believe there is singular "best" approach for Microsoft to participate in the community that is as simple as “Spend time doing X”. I think each team and each person on the team should find the approaches that best leverage the unique strengths and perspectives they bring to the table. For example: Some MSers do a really great job of answering all of the broad posts in a newsgroup, but some (like Chris Brumme http://blogs.msdn.com/cbrumme/ ) are best leveraged by sharing their in depth perspectives about the stuff they are working on. MVPs really aren't that different. Some of them DO spend a lot of time answering forum/NG questions, but some of them are MVPs because they write books or speak about areas they specialize in. All these examples are great because they get broad community reach of the unique content they can provide the community with.
I do believe it's appropriate for us to go above and beyond to spend time talking to our (Microsoft’s) best customers and influencers that can have a sizable effect on the community @ large perspectives about our products. In some cases these customers may be MVPs and in some cases they customers may simply be industry thought leaders.
It's really about ROI at times. If I can answer a newsgroup post that only I could answer that will delight a customer... I should because it is high in the uniqueness factor and tailored to my strengths. If I have the opportunity to influence the perspective of a customer, who can in turn touch thousands more customers over the next year... I should because it's high in the reach category. If I have the opportunity to maximize both reach and my unique strengths... I should make it a top priority. Like many other things in life; if you do what you are best at rather than fit into a mold you will be more passionate about the activity and you’ll be more successful and you’ll be welcomed with open arms into the community that fits you.