I am new to 10.0 and have never used the thiessen polygon tool -- i have a set of points and would like to create a thiessen polygon; what do i need to input (i.e. what type of input (.shp etc)?
Here is the ESRI help document for the Create Thiessen Polygon tool: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00080000001m000000.htm
You'll need a license for ArcInfo.
The input must be a point feature class (shapefile, geodatabase layer, etc).
You can use ArcObjects with level license ArcView: https://github.com/nicogis/Voronoi