There was a confusion in the minds of people about Zune limitations of sharing music tracks for 3 days or 3 times. “Zune allows you to listen to the song your friend sent you 3 times in 3 days. Then you have to buy the song”.

Clearification about that statement:
This 3-plays in 3-days restriction applies only to the song tracks bought from Zune Marketplace by your friend and is sent to you by him/her. This 3-plays in 3-days restrictions does not apply to any other music, songs or tracks. For example, if your friend sends you any other mp3 song (or any other non-DRM song for that matter), then this 3-plays in 3-days restriction does not apply and you can keep that song forever on your Zune and listen to it forever.

That is really a good news. What it totally means is that you can wirelessly share any music mp3 between you (which you have not bought) without any problem. Great news Microsoft.