The vodafone family thing has just appeared on their site, it's different to when I googled the other night and found the greek version, the UK version is much better.
Basically one person pays an extra 5 pound a month, they then create a group and can invite 3 other people into it. All people in the group can call each other for up to 60 minutes per call for free, calls over 60 minutes will start using inclusive minutes or standard call rates. You can invite a vodafone business customer into the group, but only calls to them are free, they cannot make free calls to other members.
Seems pretty good to me.