I’ve released version 1.0 of the Python Metadata Importer. This is a Spotlight plug-in (“mdimporter”) that gives Mac OS X 10.4 Tiger to import Python source files.
Download: Python_Metadata_Importer.dmg Source Code (BSD license). The source code shows a way of writing a Metadata importer in Python (without any dependencies on any other components).
Link to Version 1.0.1