Funnily enough, all users on G+ could be considered 30 day actives and probably most of them 7 day actives by virtue of the fact that the service is so young :)
That’s not only funny, that’s also why said difference is currently meaningless. The ten million users are also active users. The interesting question will be whether they will still be in a month (or, alternatively, whether Google+ gains so many new users that a few million lost active users don’t matter).
They are. Facebook is absolutely telling the truth about this metric. 750 million active users in the last 30 days, 50% of that daily and 80% of 750mil weekly.
I don't mean to nitpick, I'm genuinely curious: how do you know Facebook is telling the truth about the figures?
I always assumed they were telling the truth because they're legally bound to (and because if they're caught lying, it would suck badly for them). I'm just wondering if you have any more info than that, since you seem so emphatic about it.