Yes, I've looked over some of Ripple's documentation. How does a node verify the amount of XRP in existence? From what I could see the basis is supposedly a "genesis ledger" as opposed to a genesis block, but there seems to be no way to access the genesis ledger.
That's a numeric statement posted on a website. That doesn't cut it.
It looks like about in the right ballpark though, from looking at the distribution of XRP between wallets atm.
That doesn't cut it either. It needs to be mathematically verifiable.