Starting with Windows Vista Microsoft has bundled in speech recognition software, including speech dictation. This speech dictation software has an option for "Dictation Anywhere" that enables the basics of it to function with Tk apps. Advanced commands such as selection, word correction and training are not available in Tk apps. Custom widgets must support the Text Services Framework (TSF) which provides the necessary messages for interaction with Windows Speech Recnogition (WSR) system. It provides a standardized method for text services—such as voice recognition, handwriting recognition, spell checkers, and Japanese Input Method Editors—to communicate with applications and text controls. In particular, TSF allows bidirectional communication between applications and text services. This means that text services can read and write to an application’s document and an application can ask a text service to perform actions such as correcting text.
An introduction can be read at: http://msdn.microsoft.com/en-us/magazine/cc187238.aspx
Others have had questions about this as well so this wiki page will serve as a starting point for discussion and for archival of information, thoughts and ideas on making TSF and thus WSR function with Tk widgets.