Converting 2D Features to 3D

[RickKing]

The help documentation begins by saying that there are 3 ways  to accomplish this:
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00q80000009s000000.htm

The third way, by specifying a constant value, which was available in earlier versions of 3D Analyst, appears to have been omitted in ArcGIS 10.

The work around is to add an attribute with the elevation value and then use the feature to 3D using an attribute tool.

[RickKing]

After some looking, there is a way, to do this and you don't even need 3D Analyst.
ArcToolbox>Conversion Tools>To Geodatabase> Feature Class to Feature Class

Under the Environment Settings, set the Output Has Z Values = Enabled
Set Default Z Value to whatever.

BTW. The Feature Class to Feature Class tool is available in ArcCatalog by selecting Export from the context menu after right-clicking on the feature class.