Gustavo Sverzut Barbieri has built upon the gmail.py script to provide a contacts importer for GMail. The program imports a CSV file (comma delimited) from a Yahoo export and then imports those contacts into GMail. Note: Gustavo based the program around importing a Brazilian Yahoo mail export file. You will likely need to modify the code to work with exports from Yahoo in other countries.

Scripting Language: Python
export_contacts-yahoo_to_gmail.py (Source: Adrian Holovaty