The Evo 3D is currently rumored to ship with hardware that supports Near-Field Communication (NFC). More to come later....
NFC is a type (subset) of RFID (radio frequency identification) that's limited to a range of about 4 inches. In other RFID applications, the range can be a lot longer. Some credit cards already support RFID/NFC, although few merchants currently support its use. This method of payment processing has raised security concerns due to the ease one can obtain hardware to retrieve data from an RFID chip. Once a thief has a scanner, he/she can obtain the information from a credit card (or future smartphone) by bumping a pocket or a purse. With a stronger radio on the scanner, a thief can obtain the information from greater distances. The thief can then write the stolen data to a formatted magnetic-stripe card, effectively cloning the original card.
An NFC implementation on a smartphone has the potential to eliminate this vulnerability by selectively allowing the data to transmit by means of the phone's operating system or dedicated application. Whether or not the transmission can be enabled automatically or requires user intervention is yet to be determined.