After reading more about it, the only good feature seems to be the wireless, and then I thought some more... When in a social situation with an iPod if you want someone else to listen to your music so they can listen to a song or two, you give them your iPod, that way they can also look through your other music at the same time. OK so now if you both have Zune's you could send the song to each other but I'm not sure it would be that good, because it would take some of the social side away from sharing your music, as you surely wouldn't want to listen to something else on your player at the same time, and they wouldn't be able to look at any of your other music, making the whole situation kinda rude/unfriendly. I'm not convinced that any real world usage on this will occur apart from the idea sounding cool.
The final nail in the coffin is that it only works with some songs, now that is going to totally confuse the average consumer who probably thinks iTunes rips to MP3.
Other than that it's a straight iPod rip-off (though without some of the cool new features like searching) so unless it costs $199 or less I can't see many takers.