After investigating a bit, the truth is that the data is stored in the object's 'comment' parameter. Try  print keys %{$wma->comment};, and you'll see that the keys are the parameters being looked for.

Although WMA is a proprietary format, with DRM being able to encrypt files, the tagging on WMA files isn't encrypted. AFAIK, WMA feeds everything _after_ the tags into the the player, which in turn decrypts and plays the raw file. As you said, it's doubtful that intigration into the open source world will be possible, but who knows (at some point somebody may crack the encryption and although it's illegal, what will Microsoft's response be?)

WMA files at the least provide diversity with liscensing, and I personally think they could be one of Microsoft's more sucessful developments.