I spoke with the South African MVP lead back in March on this topic. He said that in his opinion (not an official MS statement) the most important quality is passion.
If a person is passionate about something then they are going to put in the time and effort to improve their skills and widen their knowledge and they are going to share that passion and knowledge with others (whether those others want it or not)
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability