The Yahoo! Music Engine description says,
Transfer music to your portable player in seconds; it’s compatible with the most popular devices (Rio, Sony, Phillips, Zen, and more)
That statement is misleading, as the antecedent Yahoo! refers to by “it” is Windows Media Audio wrapped in Microsoft’s DRM, which is not compatible with the most popular device. While I wonder how much success Yahoo will have by restricting themselves to the small portion of the portable music device market not owned by Apple, some other player could come out of nowhere and take that share, but it must be both easier and cheaper.
Meanwhile, my Panasonic RP-HS41 headphones have a short in them, so I’ll have to mosey on over to Radio Shack and pick up a new set.