Technophiles often tout RFID, or radio frequency identification, as the driver of the next revolution in the retail industry. But just when this revolution will sweep the industry -- and which vendors will benefit -- remains an open question. "It's not 'if' anymore," Lyle Ginsburg, managing partner for technology innovation in Accenture's ( ACN) Global Products Operating Group, says of RFID, a World War II era technology that can help stores better track their inventory. But Ginsburg likens the current stage of RFID adoption to the start of a marathon: "It's going to be painful until you get your rhythm or routine down." Understandably, many investors are struggling to find their stride as the potential RFID benefit is priced into names such as Zebra Technologies ( ZBRA), whose stock is trading at about 31 times forward earnings and 7 times sales, and Manhattan Associates ( MANH), a firm with a checkered past now trading at nearly 25 times forward earnings. Meanwhile, RFID revenue remains relatively minuscule at the largest hardware companies such as Texas Instruments ( TXN) and Philips Electronics ( PHG ADR). In addition, a handful of interrelated hurdles -- standards, performance and price -- remain an issue for all RFID-related ventures. Investing now in RFID is like asking how to make money on Y2K in 1994, warns Scott Lundstrum, a senior vice president and chief technology officer of AMR Research. "You can see the money out there, but you just can't get it yet."