duplicate a mesh using python?

hello, i need to duplicate a mesh using python, and i seem to be having trouble, anyone have any ideas?

Until recently this was very painful.

With the Current CVS you can do Object.Duplicate() to duplicate the current selection.

If your happy to share object data see my cookbook.
http://en.wikibooks.org/wiki/Blender_3D:_Blending_Into_Python/Cookbook#Linked_Duplicate_Object