Pointed out to me by Alber1690 in our forums
, the "pink dancing cloud" is a visualization effect that was introduced in the 2.5 spring update - and it's a visualization that's so subtle I never noticed it before. It's turned on by default, and the YouTube video below shows you where to look to see it. To make sure it's turned on, look under under Settings > Software > Display > Screen Animation, and make sure "Show screen animation" is checked off. I tested it with a song that starts off with soft vocals then kicks into high gear with a snare drum snap - and if the pink cloud surged with the song, it was so subtle I didn't even notice. So while I like that the Zune team has added a visualization tool, I think they need to give it a shot of caffeine and wake it up!