You can also purchase an unlocked iPhone from the Apple Online Store or Apple Retail Store and obtain a micro-SIM card directly from your supported GSM carrier.
Is it true ?
Theoretically, yes, that's true. Problem is finding one in stock.
You can reserve carrier-locked phones on apple.com the night before, but it does not appear that you can (yet) reserve unlocked phones - so it's just a matter of luck whether they'll have one. Or, you can reserve an AT&T phone, buy it off-contract, and "hope" that Apple doesn't decide to lock it to AT&T at some point in the future.