Dear Rob,
Your Gmail account has been hijacked!! The bad guys have your gmail account password, and are spamming the addresses in your gmail address book: your friends, the pygame list, etc.
They might have gotten your password when you logged into your Gmail account from a computer with a "trojan" infection. So I recommend that you immediately log into your gmail account from a trusted computer (a computer that you are confident has no trojan infection), and change your yahoo account password.
Then, I recommend that you scan whatever computer(s) you use for yahoo mail with some good anti-malware tools, including, at least:
(Be sure to read the paragraph at the top.)
Dave