There is little doubt that the hottest trend in MP3 players is wireless, but how it is implemented varies from device to device. Some players, such as the Zune HD and the Sony X-Series Walkman, have integrated Wi-Fi that allows for Web browsing and music-streaming capabilities (among other things). Other manufacturers go about things a bit differently, giving users the option to add wireless headphones to their devices via Bluetooth.
Unlike Wi-Fi, Bluetooth is neither good for transmitting information over a distance nor is the best way to transfer large amounts of data. However, Bluetooth requires less power and it's cheaper to operate, so it makes perfect sense for portable devices. Thanks to the proliferation of cell phones as music devices, there are plenty of decent stereo Bluetooth headphones on the market today, so if you despise wires, it's time to start considering an MP3 player with built-in Bluetooth. MP3 players with Bluetooth are getting rarer these days, but we managed to scrounge up a few that are worth your hard-earned dollars.