Noted briefly in the Wiki, but my mother came to Europe for a visit and when she used her US Visa card to make an ATM withdrawal at one of our major banks (the FX fees get refunded on her card), there was a tricky prompt showing the USD amount that was actually an attempt to get the user to accept DCC. It was when I saw the 14% markup noted that I hit 'decline' and the transaction went thru in EUR.

So DCC clearly extends to ATMs as well; not just merchant purchases.