Protect your WordPress site from attackers in 2 minutes with Authy
blog.authy.com
blog.authy.com
They have a free level for 500 authentications a month which might work for a single user but I could see that used up with a few active contributors posting often.
There is already a nice Wordpress plugin that adds Google Authenticator: http://henrik.schack.dk/google-authenticator-for-wordpress/
No it does not appear so.
But recently we've seen a huge uptick of brute force password attacks against our WP installs. These are trying common username and password combinations. To combat these attacks we've started deploying a brute force detection and blocking plugin across our entire platform. But we've also looked at adding two factor authentication as well.