http://www.fidoalliance.org/how-it-works.html
http://www.engadget.com/2013/04/24/google-joins-fido-alliance-board-support-oepn-two-factor-authentication-standard/
http://www.fidoalliance.org/board.html
Apparently the folks at Google intend repeating what Microsoft _has_already_proved_to_be_infeasible_, that is, making tokens compatible through vendor-created middleware that maps to the "right" API.
Browser-plugins is another stinker that goes exactly nowhere.
The only approach that indeed could work would be to define a specific "Web Token" and let the token vendors qualify their stuff against the platform rather than putting the burden on the _customers_ verifying which combinations of operating system, third-party middleware, browser and token that actually work.
Naturally it would been piece of cake for Microsoft or Google making Web Tokens a common thing.
However, the "Window of Opportunity" has probably gone because today everybody is chasing the mobile device market which won't use external tokens with the exception of the US government who tend to be ten years behind the rest of the IT-world.
thanx,
Anders