There was a discussion flying around Twitter yesterday about the term Jiggle Mode and when it was introduced. Someone on Reddit showed up with this video, where Steve Jobs is introducing the concept of folders in iOS 4.2.

Jump to about 18:32 for the Jiggle Mode mention.

Interesting also is the introduction of the ill-fated Ping. And the unusual “One More Thing…” at about 50:23.

UPDATE: Steve does introduce jiggling in this keynote (about 16:35 in), though he doesn’t (as far as I can tell) use the term Jiggle Mode.