I just had the misfortune to put one of those new EcoDisc’s in my Powerbooks optical drive before I saw the warning on the back. Damn did I feel suckered?! Luckily I think the publication in question intend to go back to normal DVD’s in future!
Anyway, after some fiddling I managed to get the disc out by carefully sliding a knife about an inch into the drive (avoiding the barrier in the middle of the slot) and then lifting it up as the drive tries to spit the disc out.