googlecode2github is a project designed to facilitate migrating a Google Code project to GitHub.
The GData Python client: http://code.google.com/p/gdata-python-client/downloads/list
The python-github2 client: https://github.com/ask/python-github2
The issue-transfer.py script transfers issues from Google Code to GitHub.
If you were transferring issues from a Google Code project named foobar1 to a GitHub project named foobar2, and your username is zippy, you would run the script like this:
$ python issue-transfer.py --email@example.com --google_project=foobar1 --github_username=zippy --github_project=zippy/foobar2 --github_api_token=4a9e[...]23b1
You will be prompted for your Google password so as not to require it on the command line and leave it in your .bash_history.
Here is an example of an issue (with comments) that was migrated with the script.
I've successfully migrated issues from 17 Google Code projects to GitHub with this script, but as always, proceed with caution with scripts that automatically post to Web services on your behalf.