Nobody really knows for sure what rates they are getting. Real-world rates are simply too volatile for our little tests to determine conclusively what we're getting.

That said, I know several folks who have used the Schwab ATM and credit cards overseas extensively, including in real-time "shoot outs" against other cards, and they've never been beaten. There are some other cards that yield the same exchange rates (Schwab and CapOne credit, for example, most of the time, and Schwab and TD Bank ATM cards usually yield the same rates), but we've never seen another card consistently get better rates.

Note, however, that you'll also want one or two other cards for backup just in case (even if they charge a small fee). Schwab's customer service isn't bad, but when I head overseas, in addition to Schwab I bring at minimum an AmEx credit card, a World Mastercard (mine is from Citi, which once FedExed me a replacement card in China--not every credit card provider will do that) and an ATM card with Cirrus (mine is from Citi), so I have all the possible networks covered (AmEx/MC/Visa on the CC side, and Plus/Cirrus on the ATM side) and good int'l customer service available to me.

See also the wiki that attempts to summarize this thread.