Joe, I can't say for sure; probably need to dig thru the Korean Samsung website to see whether it's a PC software or player hardware feature. Here's some other info: (Note the claim for WMA support as well as AAC/MP3)
YVP-P300 (Photo yepp II) Multiple digital audio format support - MP3, WMA, AAC... SMIL, JPEG, Text viewer include 1.8¡± TFT Color LCD 32MB Embedded flash memory & SmartMedia card slot Li-ion Battery (Long life & Rechargeable) Voice Recording High-Speed USB interface
YVP-M600D (yepp plus) Standard MPEG4 playback Multiple digital audio format support - MP3, WMA, AAC... SMIL, JPEG, Text viewer include 1.8¡± TFT Color LCD 64MB Embedded flash memory & SmartMedia card slot Li-ion Battery (Long life & Rechargeable) Voice Recording High-Speed USB interface 850K Pixel Digital camera module attachable (optional)
YP-30S (Wearable yepp) Wearable & Pendant type design Multiple digital audio format support - MP3, WMA, AAC... 64MB Embedded flash memory SDMI compliant (InterTrust plug-in) Voice Recording / 4 mode equalizer / Bass booster High-Speed USB interface
YP-MF (yepp) Multiple digital audio format support - MP3, WMA, AAC... 64MB Embedded flash memory Graphic Animation LCD display Expandable playback time with SmartMedia card EL backlight LCD on Remote Controller SDMI compliant (InterTrust plug-in) Voice Recording / 4 mode equalizer / Bass booster High-Speed USB interface