Marten Hogeweg says that the ArcGIS Editor for OpenStreetMap is available on CodePlex as an open source add-in.

Adds Marten:

If you want to contribute to documentation, best practices, or code, send your codeplex account to mhogeweg at esri dot com and I can add you to the list of contributors.

You Wichita lineman can get editing those OpenStreetMaps right away