Feature introduced in early 2014. You can enable two-step signin for your Hover account from the account settings page. Learn more: http://www.hover.com/blog/two-step-signin-is-here/
Google Authenticator support would be fantastic.
I'm already using it for LastPass, DropBox, Google Apps, and Amazon AWS.
It's free for me, and free for you guys also... in comparison to Verisign / Vasco etc...