ArcGIS 10.1 introduces Python to the list of languages for authoring Desktop add-ins, providing you with an easy solution to extend destop functionality.
Desktop add-ins are helper programs that integrate directly into ArcGIS. When you spend a lot of time in ArcGIS (creating maps, analyzing data, editing, etc.) you want tools that make you be most productive. Add-ins provide additional functionality that is not supported by geoprocessing tools such as listening and responding to ArcGIS events and interaction with the map display.
Many users have a need to create add-ins but are either unwilling or unable because of the requirement to use ArcObjects and .NET or Java. Python brings down the entry level of add-ins to users who are unable or unwilling to jump in with .NET or Java.
For help on getting started with Python add-ins, a guide book is available in the ArcGIS Desktop Help. This guidebook includes documentation and step by step examples for creating add-ins with Python.