Mesh subdivision is generally non-trivial. However, you can access mesh data directly in Unity via the Mesh class, so you can do just about whatever you want with a given mesh.
How to implement the subdivision scheme isn't really a Unity-specific issue. How to access the mesh data is of course Unity-specific, and for that I'd recommend checking the docs for the Mesh class, and maybe also looking at the procedural mesh examples that are available on the Unity site.
answered Dec 17 '10 at 02:20 AM