spam from me

Spam was sent out earlier today from my gmail account to my entire address book.

My current hypothesis is that my gmail account password was hacked. I've changed the password and am hoping that will be the end of it. I'm running a couple of up to date virus/trojan checkers (McAfee and AVG) and they are not detecting anything of significance.

Sorry for any inconvenience or confusion caused and thanks for the messages I received today informing me of the problem.

update 1: (spoofing)
A friend sent me an account of spoofing, where a worm fakes the addresses in your address book, you get bounce reports but no copies of the sent messages in the sent folder. This doesn't seem to be what is happening in my case, since the spam messages are in my sent folder.

update 2: This article recommends that you "permanently switch on SSL and use it for every action involving Gmail", the reasons why and how to do it. I have just done this. (One downside is that gmail notifier will no longer work)

update 3 (1st October, 2008): Found out that you can download a patch so that gmail notifier does work with https turned on