Maya 2012 Tutorial
How to Smooth an Object in Maya
This technique can be used to smooth and round a polygon object that has been build with a small amount of geometry. A second smoothing method involves converting your polygon object to a subdivisional surface (See Converting Polygons to Subdiv).
Create a polygon object or add a polygon primitive to the scene (Create > Polygon Primitives > Cube). In this case we set the divisions in the X, Y and Z directions to four.
Select the object and choose Mesh > Smooth. Make sure to select the smooth options.
The amount of smoothing can be controlled by adjusting the Division Levels and Continuity sliders.