Managed to get hold of a USA today article
http://www.usatoday.com/tech/product...d_x.htm?csp=34 that has a screenshot of Universal's first HD DVD title "The Bourne Supremacy" that will take better advantage of iHD. Notice the P-in-P commentary at the side (you could choose either to play the video or just audio only).
The article also mentions quite a few positive feedback from some users.