I tried it out as it's an interesting concept. Unfortunately, while I can register and also participate in the introductory badges, whenever I try to push to my backpack then confirm who I am, it seems to get stuck on authenticating me forever :(
"Threat Model<p>The reason we're even presenting the user with a dialog is because we want to prevent badge spamming, whereby third-party issuers spam a user's backpack with badges that they don't want. Consequently, we need the backpack to ask for the user's consent. This will be accomplished via an iframe embedded in the issuer's page.<p>The only sensitive information that a user needs to enter in this flow is login credentials. Since authentication is done via BrowserID, which opens in a pop-up window, the consequences of spoof attacks are minimal–so long as the user knows to look at domain names in their address bar and BrowserID's UI."<p>I was really interested until I got to this part. Asking the user for permission each time I want to award a badge? Complete fail. Mozilla doesn't get UI.