Editing Labs team has made a new editing tools for ArcGIS 10 is Curve Construction Tool. Editing tools in ArcGIS 10 will appear at the bottom of construction tools menu when you instruct the Start Editing one layer in the TOC with a polyline or polygon type.
If you are familiar with the tool Draw a Curve in Drawing for digitizing
graphic menu, then the operational Curve Construction Tool is exactly
the same. The difference, of course, directly Curve Construction Tool
generates a new shape layer. See picture below how the ease of a more
smooth digitized using a Curve Construction Tool to add a new shape to a
Download Curve Construction Tool