OpenID is an service which allows users to log on to many different web sites using a single username / password. This eliminates the need to create and remember a strong username / password for each site. The assumption, of course, is you create a strong OpenID.
Of course, if that information is lost or stolen, you're in big trouble. What if there was another level of authentication, however.
The new system, CallVerifID, uses your mobile phone to perform an extra security measure before it will authenticate you on its service. It works like this: When you want to authenticate a site using MyOpenID, first you sign on as usual, with your user ID and password. Then the service calls your phone at the number you've given it. All you have to do is pick up the phone and press # to confirm. If you don't, sign-on fails.
The only problem we could see for this is if you use your cell phone number (the most likely number as you can carry it around), and forget your phone at home, you're S.O.L.
However, it looks like (and we only tested it a couple of times) they use a consistent number to call your phone ... if this was always the case, and you have GrandCentral, you could set up GrandCentral to call multiple numbers for you.