This blog post was written by David Wynne, Product Engineer on the Geoprocessing Team in ESRI’s Software Products group in Redlands.
The Python Community announced the release of Python 2.5.4 late in December of 2008. Python 2.5.4 is a bug fixes release.
While ArcGIS 9.3.1 was shipped with Python 2.5.1, Python 2.5.4 has now been certified and is supported. In limited testing with ArcGIS 9.3, no issues were encountered. To take advantage of fixes in Python 2.5.4, it can simply be installed on top of Python 2.5.1. That means, it is not necessary to uninstall Python 2.5.1 first.*
To see and to download the release notes go here.
* If you uninstalled Python 2.5.1 and you work with the Spatial Statistics geoprocessing tools, you must reinstall Numerical Python (NumPy) from the ArcGIS installation DVDs.
For more information, see FAQ: Can Python 2.5.4 be used with ArcGIS?