e.Digital Corporation (fka EDIG)

[Tinroad]

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

http://www.ktlink.com/ces2001/korea/spec/spec_np.html