Finally got around to updating the Emacswiki page, GnusMSMTP. which is the only page I created on the wiki so far.
You can use Gnus and msmtp to send mails through the Gmail mail servers. As mentioned in the wiki site, you might need the CVS version of Gnus for it to work. Especially if you're using the stock install of Gnus that comes with Emacs 22.1.
I use the cygwin port of msmtp and it's fairly easy to get it to work.
Follow the instructions mentioned on the wiki.