Smashing Magazine posts a great article on some principles for including animation in mobile UIs.  I think the use of animation is under-estimated by some HF people because it’s hard to quanitfy the “performance benefit” (e.g., they may not increase the speed at which a user completes a task).

Some notable examples of animation are the infamous Apple’s page bounce-back, the page-curl in e-book apps or the bouncing icons on a Mac (or expanding/minimizing windows on Mac/PC).  Difficulty in quantifying objective benefits may lead some to dismiss animations as superfluous and unneccessarily ornate.  I wholeheartedly disagree.  Animations provide a fluidity that makes interfaces feel responsive even delightful.

The article provides a lot of reasons for the benefits and most appropriate use of animation. It’s typical Smashing Magazine (i.e., LOOONG) so save it to read later!

(post image from the article)