Hyper-Responsive Interaction Design
Shorter attention spans demand creative, more modern implementations of interaction design.
As it stands today, user interaction design or user experience design, or whatever the terminology you might call it by -- is effectively a creative, modern process which should illicit certain, positive emotion between the design and the user.
Twitter's update to the heart/favorite icon with a simple animation actually made me micro-smile; it's a great example of a hyper-responsive interaction.
Side note: I really need to find a screen capture program; I just slapped together a few screenshots for the GIF, heh!