Yorick over at Share-Point.blogspot.com has a good take on necessary skills for a succesfull SharePoint project.
With products like Exchange or OCS you just need a technical guy (or gall) to implement and monitor the solution.
With SharePoint, we are on a new level..
The skills you need (which means you probably need a team, and not just 1 person) include:
– technical SP
– functional SP
– SP custom development