Cedars are propagated from seeds, not branches. There's some info here: http://www.pinetum.org/advice.htm And here: http://forums.gardenweb.com/forums/load/conif/msg0404570325749.html http://forums.gardenweb.com/forums/load/conif/msg0107102919590.html
Were you asking about western red cedar (Thuja plicata) or another arborvitae? These can be grown from cuttings, try doing a search for phrases like "thuja propagation".
