Consider for a minute the ‘home’ and ‘compose new tweet’ buttons in Twitter’s new app(s).

There’s something more substantive going on here than just detailed visual design. The birdhouse and quill raise those standard metaphors to a level that takes into account the ethos of the product itself. They’re right in what I think of as the delight layer of UX. It’s the stuff that has little to no effect on utility, but enriches the app in a way that wouldn’t quite work with any other product.

In other words, this layer doesn’t necessarily make the product any easier to use – but it contains cues, markers and behaviors that are almost intangible, yet endow the product with unique experiential qualities.

I’ll leave the rest of the app for others to review/criticize/praise, but in my mind this is a brilliant, nontrivial touch.